Add a KB argument to PWToPartition.

Add a KB argument to PWToPartition.

Currently isn't used anywhere, but without it the 2nd argument to PWToPartition
which is passed down to `condition' will be silently swallowed by the newly
added KB argument of `condition'.

#This module implements `Partition`---Hakaru's replacement for Maple's
#endogenous and unwieldy `piecewise`.

#The outer data structure for a Partition is a function, PARTITION(...), (just like it
#is for piecewise.
Partition:= module()
  option package;

  # Constructor for Partition pieces
  global Piece;

local
  Umap := proc(f,x,$)
    f(op(0,x))( map( p -> Piece(f(condOf(p)),f(valOf(p))), piecesOf(x) )
              , `if`(nops(x)>1,map(f,[op(2..-1,x)]),[])[] )
  end proc,

  isPartitionPieceOf := proc( p, elem_t := anything )
    type(p, 'Piece(PartitionCond, elem_t)');
  end proc,

  isPartitionOf := proc( e, elem_t := anything )
    type(e, 'PARTITION(list(PartitionPiece(elem_t)))' ) or
    type(e, 'PARTITION(list(PartitionPiece(Or(elem_t,PieceRef))),list(elem_t))' );
  end proc,

  TYPES := table(
    [(PieceRef = 'And(specfunc(nonnegint,PieceRef),satisfies(x->nops(x)>0))')
    ,(PartitionCond = '{relation, boolean, `::`, specfunc({`And`,`Or`,`Not`}), `and`, `or`, `not`}')
    ,(PartitionPiece = 'isPartitionPieceOf')
    ,(Partition = 'isPartitionOf')
    ]),

  ModuleLoad::static:= proc()
    :-`print/PARTITION`:= proc()
      local SetOfRecords, branch;
      SetOfRecords := piecesOf(PARTITION(args));
      `print/%piecewise`(
        seq([ condOf(eval(branch)), valOf(eval(branch))][], branch= SetOfRecords))
    end proc;

    BindingTools:-load_types_from_table(TYPES);

    # global extensions to maple functionality
    :-`eval/PARTITION` :=
    proc(p, eqs, $)
      Umap(x->eval(x,eqs), p);
    end proc;

    # :-`depends/PARTITION` :=
    # proc(parts, nms, $)
    # local dp := (x -> depends(x, nms));
    #   # `or`(op ( map(p-> dp(condOf(p)) or dp(valOf(p)), parts) ), dp(x,);
    # end proc;

    :-`diff/PARTITION` := proc()
      local pw, wrt, dpw, r, r0, r1;
      wrt := args[-1];
      pw := PARTITION(args[1..-2]);
      pw  := PartitionToPW(pw);
      dpw := diff(pw, wrt);
      r   := PWToPartition(dpw, 'do_solve');
      r   := Pmap(simplify, r);
    end proc;

    :-`simplify/PARTITION` := Simpl;

    :-`convert/piecewise` := overload(
      [proc(p::Partition)
         option overload(callseq_only);
         PartitionToPW(p);
       end proc, :-`convert/piecewise`]);

    unprotect(:-solve);
    :-`solve` := overload([
      proc(x:: Not(freeof(`PARTITION`))  )
        option overload(callseq_only); FAIL;
      end proc, :-`solve`]);
    protect(:-solve);

    VerifyTools[AddVerification](same_partition = proc(a,b,$) evalb(a=b) or SamePartition((x,y)->evalb(x=y),(x,y)->evalb(x=y),a,b) end proc);

    NULL
  end proc,

  ModuleUnload::static:= proc()
    NULL
  end proc,

  # abstract out all argument checking for map-like functions
  map_check := proc(p)
  local pos, err;
    if p::indexed then
      pos:= op(p);
      if not [pos]::[posint] then
        err := sprintf("Expected positive integer index; received %a", [pos]);
        return err;
      end if
    else
      pos:= 1
    end if;
    if nargs-1 <= pos then
      err := sprintf("Expected at least %d arguments; received %d", pos+1, nargs-1);
      return err;
    end if;
    if not args[pos+2]::Partition then
      err := sprintf("Expected a Partition; received %a", args[pos+2]);
      return err;
    end if;
    return pos;
  end proc,

  extr_conjs := proc(x,$)
    if x::{specfunc(`And`), `and`} then
      map(extr_conjs, [op(x)])[];
    else
      x
    end if
  end proc;
export
  piecesOf := proc(x, $)
    local ps, rs;
    ps := op(1,x);
    if nops(x)=2 then
      rs := op(2,x);
      ps := map(mapPiece(proc(c0,v0)
                  local c,c1,v,s; c,v := c0,v0; s := (x->x);
                  if v::PieceRef then
                    c1 := is_lhs(type,c,name);
                    if c1<>FAIL then s := x->subs(c1,x) end if;
                    c, s(op(op(1,v),rs))
                  else
                    c, v
                  end if; end proc), ps );
    elif has(x,PieceRef) then
      error "found piece references (%1) but no table of pieces: %2", indets(x,PieceRef), x
    end if;
    ps;
  end proc,

  condOf := proc(x::specfunc(`Piece`),$)
    op(1,x);
  end proc,

  valOf := proc(x::specfunc(`Piece`),$)
    op(2,x);
  end proc,

  mapPiece := proc(f,$) proc(x::PartitionPiece,$) Piece(f(condOf(x), valOf(x))) end proc; end proc,
  unPiece := mapPiece(ident),
  ident := proc() args end proc,
  is_lhs := proc(test,x0)
    local x := x0;
    if test(rhs(x),_rest) then x := op(0,x)(rhs(x),lhs(x)) end if;
    if test(lhs(x),_rest) then return x
    else                       return FAIL
    end if;
  end proc,

  # This is an alternate (to PARTITION) constructor for partition, which has the
  # same call convention as piecewise, except there are no implicit cases. if
  # there is an otherwise case, its condition is the conjunction of negations of
  # the other conditions.
  ModuleApply := proc()::Partition;
    local ps, as, ops_r;
    if nargs=0 then
      error "empty partition";
    end if;
    ps := [args]; ops_r := iquo(nops(ps),2);
    if nops(ps)::odd then
      ps := [op(1..-2,ps), Not(bool_Or(seq(op(2*i-1,ps),i=1..ops_r))), op(-1,ps)];
      ops_r := ops_r+1;
    end if;
    ps := [seq(Piece(op(2*i-1,ps),op(2*i,ps)),i=1..ops_r)];
    PARTITION(ps);
  end proc,

  Pieces := proc(cs0,es0)::list(PartitionPiece);
    local es, cs;
    es := `if`(es0::{set,list},x->x,x->{x})(es0);
    cs := `if`(cs0::{set,list,specfunc(`And`),`and`},x->x,x->{x})(cs0);
    [seq(seq(Piece(c,e),c=cs),e=es)];
  end proc,

  #This is just `map` for Partitions.
  #Allow additional args, just like `map`
  Pmap::static:= proc(f)::Partition;
    local pair,pos,res;
    res := map_check(procname, args);
    if res::string then error res else pos := res; end if;
    PARTITION([seq(
      Piece(condOf(pair)
            ,f(args[2..pos], valOf(pair), args[pos+2..])
         ),pair= piecesOf(args[pos+1]))])
  end proc,

  # a more complex mapping combinator which works on all 3 parts
  # not fully general, but made to work with KB
  # also, does not handle extra arguments (on purpose!)
  Amap::static:= proc(
    funcs::[anything, anything, anything], #`appliable` not inclusive enough.
    part::Partition)::Partition;
    local pair,pos,f,g,h,doIt;
    (f,g,h) := op(funcs);
    #sigh, we don't have a decent 'let', need to use a local proc
    doIt := proc(pair)
    local kb0 := h(condOf(pair));
      Piece( f(condOf(pair), kb0),
             g(valOf(pair), kb0));
    end proc;
    PARTITION(map(doIt,piecesOf(part)));
  end proc,

  Foldr := proc( cons, nil, prt :: Partition, $ )
    foldr(proc(p, x) cons(condOf(p), valOf(p), x); end proc,nil,op(piecesOf(prt)));
  end proc,

  Case := proc(ty,f,g) proc(x) if x::ty then f(x) else g(x) end if end proc end proc,
  Foldr_mb := proc(cons,nil,prt) Case(Partition, x->Foldr(cons,nil,x), x->cons(true,x,nil)) end proc,
  PartitionToPW_mb := Case(Partition, PartitionToPW, x->x),
  PWToPartition_mb := Case(specfunc(piecewise), PWToPartition, x->x),

  PartitionToPW := module()
    export ModuleApply; local pw_cond_ctx;
    ModuleApply := proc(x::Partition, $)
      local parts := piecesOf(x);
        if nops(parts) = 1 and is(op([1,1],parts)) then return op([1,2], parts) end if;
        parts := foldl(pw_cond_ctx, [ [], {} ], op(parts) );
        parts := [seq([condOf(p), valOf(p)][], p=op(1,parts))];
        if op(-2, parts) :: identical(true) then
          parts := subsop(-2=NULL, parts);
      end if;
      piecewise(op(parts));
    end proc;

    pw_cond_ctx := proc(ctx_, p, $)
    local ps, ctx, ctxN, cond, ncond;
      ps, ctx := op(ctx_); cond := condOf(p);
      cond := {extr_conjs(cond)};
      cond := remove(x->x in ctx, cond);
      ncond := `if`(nops(cond)=1
                    , KB:-negate_rel(op(1,cond))
                    , `Not`(bool_And(op(cond))) );
      cond := bool_And(op(cond));
      ctx := ctx union { ncond };
      [ [ op(ps), Piece(cond, valOf(p)) ], ctx ]
    end proc;
  end module,

  isShape := kind ->
  module()
    option record;

    export MakeCtx := proc(p0,_rec)
      local p := p0, pw, p1, wps, ws, vs, cs, w, ps;
      if kind='piecewise' then
        p := Partition:-PWToPartition(p);
      end if;
      w, p1 := Partition:-Simpl:-single_nonzero_piece(p);
      if not w :: identical(true) or p1 <> p then
        [ w, p1 ]
      else
        ps := piecesOf(p);
        wps := map(_rec@valOf, ps);
        ws, vs, cs := map2(op, 1, wps), map2(op, 2, wps), map(condOf, ps);
        if nops(vs) > 0 and
          andmap(v->op(1,vs)=v, vs) and
          ormap(a->a<>{}, ws)
        then
          [ `bool_Or`( op( zip(`bool_And`, ws, cs) ) ) , op(1,vs) ];
        else
          [ true, p0 ];
        end if;
      end if;
    end proc;
    export MapleType := `if`(kind=`PARTITION`,'Partition','specfunc(piecewise)');
  end module,

  # Checks if the given Partition is semantically valid, i.e. the conditions are
  # all disjoint. This exploits the property that if each adjacent pair of
  # conditions is pairwise disjoint, then they are all disjoint
  # (i.e. disjointness is transitive).
  IsValid := proc(p::Partition,$)
    local i, cs; cs := map(condOf, piecesOf(p));
    for i from 2 to nops(cs) do
      if (coulditbe(op(i  ,cs)) assuming op(i-1,cs)) or
         (coulditbe(op(i-1,cs)) assuming op(i  ,cs)) then
        return false; end if;
    end do;
    return true;
  end proc,

  # convert a piecewise to a partition, which is straightforward except:
  # - if any of the branches are unreachable, they are removed
  # - if the last clause is (implicitly) `otherwise`, that clause is filled in
  #     appropriately
  # note that if the piecewise does not cover the entire domain,
  #   then this Partition will be 'invalid' (in the sense that it also
  #   will not cover the entire domain) - the 'correct' thing to do would
  #   probably be to add a new clause whose value is 'undefined'
  # the logic of this function is already essentially implemented, by KB
  # in fact, kb_piecewise does something extremely similar to this
  PWToPartition := proc(x::specfunc(piecewise), {_kb::t_kb:=KB:-empty})::Partition;
    # each clause evaluated under the context so far, which is the conjunction
    # of the negations of all clauses so far
    local ctx := true, n := nops(x), cls := [], cnd, ncnd, i, q, ctxC, cl, p;

    # Checks if the piecewise is valid when translated literally to a Partition
    # if so, that Partition can be returned directly. This is not done by
    # default because the check calls `coulditbe' many times which is
    # potentially much more expensive than just building the Partition from
    # scratch. This should only be used when the piecewise comes from a solver
    # which may or may not already return a 'partition', and when it does return
    # a 'partition', the set of conditions is typically so complicated that
    # rebuilding it produces an unwieldy monster (e.g. SemiAlgebraic in the case
    # of e.g. RoundTrip/t62).
    if 'check_valid' in {_rest} then
      p := Partition(op(x));
      if IsValid(p) then return p end if;
    end if;

    # handles all but the `otherwise` case if there is such a case
    for i in seq(q, q = 1 .. iquo(n, 2)) do
      cnd := op(2*i-1,x); # the clause as given
      # if this clause is unreachable, then every subsequent clause will be as well
      if ctx :: identical(false) then return PARTITION( cls );
      else
        ctxC := `And`(cnd, ctx);              # the condition, along with the context (which is implicit in pw)
        ctxC := Simpl:-condition(ctxC, _kb, _rest);

        if cnd :: `=` then ncnd := lhs(cnd) <> rhs(cnd);
        else               ncnd := Not(cnd) end if;

        ctx  := `And`(ncnd, ctx);             # the context for the next clause

        if ctx :: identical(false,[]) then    # this clause is actually unreachable
          return(PARTITION(cls));
        else
          cls := [ op(cls), op(Pieces(ctxC,[op(2*i,x)])) ];
        end if;
      end if;
    end do;

    # if there is an otherwise case, handle that.
    if n::odd then
      ctx := Simpl:-condition(ctx, _kb, _rest);
      if not ctx :: identical(false,[]) then
        cls := [ op(cls), op(Pieces(ctx,[op(n,x)])) ];
      end if;
    end if;

    if nops(cls) = 0 then
      WARNING("PWToPartition: the piecewise %1 produced an empty partition", x);
      return 0;
    end if;
    PARTITION( cls );
  end proc,

  # applies a function to the arg if arg::Partition,
  # and if arg::piecewise, then converts the piecewise to a partition,
  # applies the function, then converts back to piecewise
  # this mainly acts as a sanity check
  AppPartOrPw := proc(f,x::Or(Partition,specfunc(piecewise)))
    if x::Partition then f(x);
    else                 PartitionToPW(f(PWToPartition(x))) end if;
  end proc,

  #Check whether the conditions of a Partition satisfy a type (or a proc return
  #truefalse)
  ConditionsSatisfy := proc(P::Partition, test, $)
    local p, ty; ty := `if`(test::type,test,satisfies(test));
    for p in piecesOf(P) do if condOf(p)::ty then return true end if end do;
    false
  end proc,

  #Check whether the conditions of a Partition depend on any of a set of names.
  ConditionsDepend:= proc(P::Partition, V::{name, list(name), set(name)}, $)
    ConditionsSatisfy(P, x->depends(x,V));
  end proc,

  # The cartesian product of two Partitions
  PProd := proc(p0::Partition,p1::Partition,{_add := `+`})::Partition;
  local ps0, ps1, cs, rs, rs0, rs1;
    ps0,ps1 := map(ps -> sort(piecesOf(ps), key=(z->condOf(z))), [p0,p1])[];
    cs := zip(proc(p0,p1)
                if condOf(p0)=condOf(p1) then
                  Piece(condOf(p0),_add(valOf(p0),valOf(p1))) ;
                else [p0,p1];
                end if;
              end proc, ps0,ps1);
    rs, cs := selectremove(c->type(c,list),cs);
    rs0, rs1 := map(k->map(r->op(k,r),rs),[1,2])[];
    rs := map(r0->map(r1-> Piece( bool_And(condOf(r0),condOf(r1)), _add(valOf(r0),valOf(r1)) )
                      ,rs1)[],rs0);
    PARTITION([op(cs),op(rs)]);
  end proc,

  Simpl := module()
    export ModuleApply := proc(p)
      option remember, system;
      local ps, qs, qs1, mk, as; as := _rest;
      if p :: Partition then
        foldr((f,x)->f(x,as), p,
              reduce_branches,
              remove_false_pieces,
              flatten,
              singular_pts);
      elif assigned(distrib_op_Partition[op(0,p)]) then
        mk := distrib_op_Partition[op(0,p)];
        ps := [op(p)];
        ps := map(x->Simpl(x,as), ps);
        ps, qs := selectremove(type, ps, Partition);
        if nops(ps)=0 then return p end if;
        mk(op(qs),foldr(((a,b)->
                         remove_false_pieces(Partition:-PProd(a,b,_add=mk))),
                        op(ps)));
      else
        subsindets(p,{Partition,indices(distrib_op_Partition,nolist)},x->Simpl(x,_rest));
      end if;
    end proc;
    export distrib_op_Partition := table([`+`=`+`,`*`=`*`]);

    export flatten := module()
      export ModuleApply;
      local unpiece, unpart, flatten_with;

      ModuleApply := proc(pr0, { _with := [ 'Partition', unpart ] } )
        local ty, un_ty, pr1, pr2;
        ty, un_ty := op(_with);

        pr1 := subsindets(pr0, ty, un_ty);
        if pr0 <> pr1 then
          ModuleApply(pr1, _with=[ Or('Partiton',`*`), unpart ]);
        else
          pr0
        end if;
      end proc;

      # like Piece, but tries to not be a Piece
      unpiece := proc(c, pr, $)
        flatten_with(proc(mk_q, ps)
                       map(q -> Piece(bool_And(condOf(q),c),mk_q(valOf(q))), ps)[]
                     end proc,
                     x->Piece(c,x),
                     pr);
      end proc;

      unpart := curry(
        flatten_with,proc(mk_q, ps)
                       PARTITION(map(q -> unpiece(condOf(q),valOf(q)), ps))
                     end proc, x->x);

      flatten_with := proc(rec, fail, pr, $)
      local ps, ws;
        if pr :: Partition then
          ps := piecesOf(pr); ws := [];
        elif pr :: `*` then
          ps, ws := selectremove(q->type(q,Partition), [op(pr)]);
          if nops(ps) = 1 then
            ps := piecesOf(op(1,ps));
          else return fail(pr) end if;
        else
          return fail(pr);
        end if;
        rec(x->`*`(op(ws),x), ps);
      end proc;
    end module;

    export single_nonzero_piece_cps := proc(k)
      local r,p; r, p := single_nonzero_piece(_rest);
      if r :: identical(true) then
        args[2]
      else
        k(r, p);
      end if;
    end proc;

    export single_nonzero_piece := proc(e, { _testzero := Testzero })
      local zs, nzs;
      if e :: Partition then
        zs, nzs := selectremove(p -> _testzero(valOf(p)), piecesOf(e));
        if nops(nzs) = 1 then
          return condOf(op(1,nzs)) , valOf(op(1,nzs))
        end if;
      end if;
      true, e
    end proc;

    export remove_false_pieces := proc(e::Partition, kb := KB:-empty)
      PARTITION(remove(p -> type(KB:-assert(condOf(p), kb), t_not_a_kb), piecesOf(e)));
    end proc;

    local `&on` := proc(f,k,$) proc(a,b,$) f(k(a),k(b)) end proc end proc;
    local condition_complexity := proc(x)
      nops(indets(x,PartitionCond)) + nops(indets(x,specfunc({exp, ln})))
    end proc;

    export reduce_branches := proc(e::Partition, kb := KB:-empty, { _testequal := ((a,b) -> Testzero(a-b)) })
      local k, ks, i, vs, ps1, ps; ps := piecesOf(e); vs := map(valOf,ps);
      userinfo(3, :-reduce_branches, printf("Input: %a\n", ps));

      if nops(ps)=1 then return op([1,2],ps); end if;

      # Categorize(group) by equality of piece values
      ps1 := [ListTools:-Categorize(_testequal &on valOf, ps)];
      # unless there are fewer groups than original pieces ...

      ks  := map(nops, ps1); # number of pieces per group

      # build the result
      ps1 := map(p->Piece(bool_Or(condition(bool_Or(map(condOf,p)[]), kb,
                                            'do_solve', 'do_kb', 'do_check')[])
                          ,valOf(op(1,p)))
                 ,ps1);
      userinfo(3, :-reduce_branches, printf("condition: %a\n", ps1));

      # replace the condition of each piece built from many others
      if nops(ps1) < nops(ps) and nops(ps1)>1 then
        for i in select(x->op(1,x)>1,sort(zip(`[]`,ks,[seq(1..nops(ks))]), key=(x->-op(1,x)))) do
          ps1 := piecesOf( replace_piece_cond(PARTITION(ps1), op(2,i)) );
        end do;
      end if;

      return PARTITION(ps1);
    end proc;

    # Replaces a piece (at given index) condition with the logically equivalent
    # one formed from the other pieces.
    export replace_piece_cond := proc(e::Partition, n::integer := -1, failure:=(x->x), cmp_score := [ (x->x), (x->x+1) ], $)
      local p_n, p_n1,ps,cmp; ps := piecesOf(e);
      if abs(n)>nops(ps) then
        error "index out of bound: %1", n;
      elif nops(ps)=1 then
        error "cannot replace in single piece Partition: %1", e
      end if;
      p_n := condOf(op(n, ps));                              # old condition
      p_n1 := Not(bool_Or(map(condOf,subsop(n=NULL,ps))[])); # new condition
      cmp := map(condition_complexity, [p_n1, p_n]);

      # a cheap metric for determining if the new condition is an improvement
      if `<=`(zip(apply, cmp_score, cmp)[]) then
        ps := subsop([n,1]=p_n1, ps);
        PARTITION(ps);
      else
        failure(PARTITION(ps));
      end if;
    end proc;

    # Removal of singular points from partitions
    # works with other things too!
    export singular_pts := module()
      local t_constant := (ns->x->(indets(x,And(name,Not(constant))) minus ns)={});
      local can_remove := proc(ns)
        local t1, t2;
        t1 := satisfies(t_constant(ns));
        t2 := satisfies(n->n in ns);
        'Or'(`=`(t2,{t1,t2}),`=`(t1,t2));
      end proc;

      local weakening := {`<=`=`<`, `>=`=`>`};
      local can_replace := proc(ns)
        local t := satisfies(n->n in ns);
        'And'('specfunc'(map(lhs,weakening)),
              {'anyfunc'('anything',t),'anyfunc'(t,'anything')});
      end proc;
      local do_replace := proc(c)
        table([op(weakening)])[op(0,c)](op(c));
      end proc;

      export ModuleApply := proc(sh, kb::t_kb:=KB:-empty,{_name_cands::list := [] })
        local ns, sh1; sh1 := sh;
        # todo: work with array types as well?
        ns := select(type, [op(kb)], And(KB:-t_kb_Introduce,anyfunc(anything,specfunc({`AlmostEveryReal`,`HReal`}))));
        ns := map(curry(op,1), ns);
        ns := { op(ns), op(_name_cands) };
        if ns={} then return sh end if;

        sh1 := subsindets(sh1, can_remove(ns), _->false);
        sh1 := eval(eval(sh1, [`And`=bool_And,`Or`=bool_Or]));
        sh1 := subsindets(sh1, 'specfunc'('specfunc'(map(op,weakening)),Not), bool_Not@op);
        sh1 := subsindets(sh1, can_replace(ns), do_replace);
        subsindets[flat](sh1, Partition, pr->remove_false_pieces(pr,kb));
      end proc;
    end module; # singular_pts

    export condition := module()
      local is_extra_sol := x -> (x :: `=` and rhs(x)=lhs(x) and lhs(x) :: name);
      local postproc_for_solve := proc(ctx, ctxSlv)
                               ::{identical(false), list({boolean,relation,specfunc(boolean,And),`and`(boolean)})};
        local ctxC := ctxSlv;
        if ctxC = [] then
          ctxC := [] ;
        elif nops(ctxC)> 1 then
          ctxC := map(x -> postproc_for_solve(ctx, [x], _rest)[], ctxC);
        elif nops(ctxC) = 1 then
          ctxC := op(1,ctxC);
          if ctxC :: set then
            if ctxC :: identical('{}') then
              ctxC := NULL;
            else
              ctxC := remove(is_extra_sol, ctxC);
               # if all the solutions are 'extra', the solution is actually just
               # garbage. Maple can't really tell and doesn't just return the
               # empty set (no solutions) for these cases.
              if ctxC = {} then
                ctxC := ctx;
              else
                ctxC := bool_And(op(ctxC));
              end if;
            end if ;
            ctxC := [ctxC];
          elif ctxC :: specfunc('piecewise') then
            ctxC := PWToPartition(ctxC, _rest);
            ctxC := [ seq( map( o -> condOf(c) and o
                                , postproc_for_solve(ctx, valOf(c), _rest))[]
                           , c=piecesOf(ctxC) )] ;
          else
            ctxC := FAIL;
          end if;
        else
          ctxC := FAIL;
        end if;
        if ctxC = FAIL then
          error "don't know what to do with %1", ctxSlv;
        else
          ctxC;
        end if;
      end proc;

      # For some reason, solve just disregards these sorts of conditions
      # altogether, but not when they appear on their own! e.g.
      #  solve( {a<>b} )       = {a=a,a<>b}
      #  solve( {Not(a<>b)} )  = {a=a,b=b}  -- but should be {..,a=b}
      local can_solve := proc(c,$)
        local neq_nn := `<>`(name,name);
        evalb(indets(c, neq_nn) = {} or not has(c,`idx`))
      end proc;

      export ModuleApply := proc(ctx, kb::t_kb := KB:-empty)::list(PartitionCond);
        option remember, system;
        local ctxC, ctxC1, ctxC_c, ctxC1_c;
        ctxC := ctx;
        if ctx :: identical(true) then
          error "Simpl:-condition: don't know what to do with %1", ctxC;
        end if;
        if 'do_kb' in {_rest} then
          ctxC1 := KB:-kb_subtract( KB:-assert( ctxC, kb ), kb );
          if nops(ctxC1)=1 and op([1,1], ctxC1)=KB:-assert then
            ctxC1 := op([1,2], ctxC1);
            ctxC1_c, ctxC_c := map(condition_complexity, [ctxC1,ctxC])[];
            if ctxC1_c < ctxC_c then
              ctxC := ctxC1;
            end if;
          end if;
        end if;
        if condition_complexity(ctxC)=1 then
          return [ctxC];
        end if;

        ctxC := KB:-chill(ctxC);

        if 'do_solve' in {_rest} and _Env_HakaruSolve<>false and can_solve(ctxC) then
          ctxC1 := solve({ctxC}, 'useassumptions'=true);
          if ctxC1 = ctxC then
            # sometimes solve returns unevaluated which confuses postproc because
            # it expects the typical output of solve
            ctxC := [ctxC];
          elif ctxC1 = NULL and indets(ctx, specfunc(`exp`)) <> {} then
            ctxC := [ctxC];
          else
            ctxC1 := postproc_for_solve(ctxC, [ctxC1], _rest);
            if 'do_check' in {_rest} and condition_complexity(ctxC)>condition_complexity(ctxC1) then
              ctxC := ctxC1;
            end if;
          end if;
          if indets(ctxC, specfunc({`Or`, `or`})) <> {} then
            userinfo(10, 'Simpl:-condition',
                     printf("output: \n"
                            "  %a\n\n"
                            , ctxC ));
          end if;
        else
          ctxC1 := ctxC;
          ctxC := [seq(Domain:-simpl_relation(ctxC1, norty=t), t=['DNF','CNF'])];
          ctxC := eval(ctxC,`And`=bool_And);
          ctxC := op(1, sort(ctxC, key=condition_complexity));
          if ctxC :: specfunc(`Or`) then
            ctxC := [op(ctxC)]
          else
            ctxC := [ctxC];
          end if;
        end if;
        if 'no_split_disj' in {_rest} then
          ctxC := [ bool_Or(op(ctxC)) ];
        end if;
        ctxC := KB:-warm(ctxC);
        `if`(ctxC::list, ctxC, [ctxC]);
      end proc;
    end module; #Simpl:-condition
  end module, #Simpl

  SamePartition := proc(eqCond, eqPart, p0 :: Partition, p1 :: Partition, $)
    local ps0, ps1, pc0, the;
    ps0, ps1 := map(piecesOf,[p0,p1])[];
    if nops(ps0) <> nops(ps1) then return false end if;
    for pc0 in ps0 do
      the, ps1 :=
        selectremove(pc1 ->
          eqCond( condOf(pc1), condOf(pc0) ) and
          eqPart( valOf(pc1) , valOf(pc0)  )     ,ps1);
      if nops(the) <> 1 then
        return false;
      end if;
    end do;
    true;
  end proc
;
  uses Hakaru;
  ModuleLoad();
end module:

#This module implements `Partition`---Hakaru's replacement for Maple's
#endogenous and unwieldy `piecewise`.

#The outer data structure for a Partition is a function, PARTITION(...), (just like it
#is for piecewise.
Partition:= module()
  option package;

  # Constructor for Partition pieces
  global Piece;

local
  Umap := proc(f,x,$)
    f(op(0,x))( map( p -> Piece(f(condOf(p)),f(valOf(p))), piecesOf(x) )
              , `if`(nops(x)>1,map(f,[op(2..-1,x)]),[])[] )
  end proc,

  isPartitionPieceOf := proc( p, elem_t := anything )
    type(p, 'Piece(PartitionCond, elem_t)');
  end proc,

  isPartitionOf := proc( e, elem_t := anything )
    type(e, 'PARTITION(list(PartitionPiece(elem_t)))' ) or
    type(e, 'PARTITION(list(PartitionPiece(Or(elem_t,PieceRef))),list(elem_t))' );
  end proc,

  TYPES := table(
    [(PieceRef = 'And(specfunc(nonnegint,PieceRef),satisfies(x->nops(x)>0))')
    ,(PartitionCond = '{relation, boolean, `::`, specfunc({`And`,`Or`,`Not`}), `and`, `or`, `not`}')
    ,(PartitionPiece = 'isPartitionPieceOf')
    ,(Partition = 'isPartitionOf')
    ]),

  ModuleLoad::static:= proc()
    :-`print/PARTITION`:= proc()
      local SetOfRecords, branch;
      SetOfRecords := piecesOf(PARTITION(args));
      `print/%piecewise`(
        seq([ condOf(eval(branch)), valOf(eval(branch))][], branch= SetOfRecords))
    end proc;

    BindingTools:-load_types_from_table(TYPES);

    # global extensions to maple functionality
    :-`eval/PARTITION` :=
    proc(p, eqs, $)
      Umap(x->eval(x,eqs), p);
    end proc;

    # :-`depends/PARTITION` :=
    # proc(parts, nms, $)
    # local dp := (x -> depends(x, nms));
    #   # `or`(op ( map(p-> dp(condOf(p)) or dp(valOf(p)), parts) ), dp(x,);
    # end proc;

    :-`diff/PARTITION` := proc()
      local pw, wrt, dpw, r, r0, r1;
      wrt := args[-1];
      pw := PARTITION(args[1..-2]);
      pw  := PartitionToPW(pw);
      dpw := diff(pw, wrt);
      r   := PWToPartition(dpw, 'do_solve');
      r   := Pmap(simplify, r);
    end proc;

    :-`simplify/PARTITION` := Simpl;

    :-`convert/piecewise` := overload(
      [proc(p::Partition)
         option overload(callseq_only);
         PartitionToPW(p);
       end proc, :-`convert/piecewise`]);

    unprotect(:-solve);
    :-`solve` := overload([
      proc(x:: Not(freeof(`PARTITION`))  )
        option overload(callseq_only); FAIL;
      end proc, :-`solve`]);
    protect(:-solve);

    VerifyTools[AddVerification](same_partition = proc(a,b,$) evalb(a=b) or SamePartition((x,y)->evalb(x=y),(x,y)->evalb(x=y),a,b) end proc);

    NULL
  end proc,

  ModuleUnload::static:= proc()
    NULL
  end proc,

  # abstract out all argument checking for map-like functions
  map_check := proc(p)
  local pos, err;
    if p::indexed then
      pos:= op(p);
      if not [pos]::[posint] then
        err := sprintf("Expected positive integer index; received %a", [pos]);
        return err;
      end if
    else
      pos:= 1
    end if;
    if nargs-1 <= pos then
      err := sprintf("Expected at least %d arguments; received %d", pos+1, nargs-1);
      return err;
    end if;
    if not args[pos+2]::Partition then
      err := sprintf("Expected a Partition; received %a", args[pos+2]);
      return err;
    end if;
    return pos;
  end proc,

  extr_conjs := proc(x,$)
    if x::{specfunc(`And`), `and`} then
      map(extr_conjs, [op(x)])[];
    else
      x
    end if
  end proc;
export
  piecesOf := proc(x, $)
    local ps, rs;
    ps := op(1,x);
    if nops(x)=2 then
      rs := op(2,x);
      ps := map(mapPiece(proc(c0,v0)
                  local c,c1,v,s; c,v := c0,v0; s := (x->x);
                  if v::PieceRef then
                    c1 := is_lhs(type,c,name);
                    if c1<>FAIL then s := x->subs(c1,x) end if;
                    c, s(op(op(1,v),rs))
                  else
                    c, v
                  end if; end proc), ps );
    elif has(x,PieceRef) then
      error "found piece references (%1) but no table of pieces: %2", indets(x,PieceRef), x
    end if;
    ps;
  end proc,

  condOf := proc(x::specfunc(`Piece`),$)
    op(1,x);
  end proc,

  valOf := proc(x::specfunc(`Piece`),$)
    op(2,x);
  end proc,

  mapPiece := proc(f,$) proc(x::PartitionPiece,$) Piece(f(condOf(x), valOf(x))) end proc; end proc,
  unPiece := mapPiece(ident),
  ident := proc() args end proc,
  is_lhs := proc(test,x0)
    local x := x0;
    if test(rhs(x),_rest) then x := op(0,x)(rhs(x),lhs(x)) end if;
    if test(lhs(x),_rest) then return x
    else                       return FAIL
    end if;
  end proc,

  # This is an alternate (to PARTITION) constructor for partition, which has the
  # same call convention as piecewise, except there are no implicit cases. if
  # there is an otherwise case, its condition is the conjunction of negations of
  # the other conditions.
  ModuleApply := proc()::Partition;
    local ps, as, ops_r;
    if nargs=0 then
      error "empty partition";
    end if;
    ps := [args]; ops_r := iquo(nops(ps),2);
    if nops(ps)::odd then
      ps := [op(1..-2,ps), Not(bool_Or(seq(op(2*i-1,ps),i=1..ops_r))), op(-1,ps)];
      ops_r := ops_r+1;
    end if;
    ps := [seq(Piece(op(2*i-1,ps),op(2*i,ps)),i=1..ops_r)];
    PARTITION(ps);
  end proc,

  Pieces := proc(cs0,es0)::list(PartitionPiece);
    local es, cs;
    es := `if`(es0::{set,list},x->x,x->{x})(es0);
    cs := `if`(cs0::{set,list,specfunc(`And`),`and`},x->x,x->{x})(cs0);
    [seq(seq(Piece(c,e),c=cs),e=es)];
  end proc,

  #This is just `map` for Partitions.
  #Allow additional args, just like `map`
  Pmap::static:= proc(f)::Partition;
    local pair,pos,res;
    res := map_check(procname, args);
    if res::string then error res else pos := res; end if;
    PARTITION([seq(
      Piece(condOf(pair)
            ,f(args[2..pos], valOf(pair), args[pos+2..])
         ),pair= piecesOf(args[pos+1]))])
  end proc,

  # a more complex mapping combinator which works on all 3 parts
  # not fully general, but made to work with KB
  # also, does not handle extra arguments (on purpose!)
  Amap::static:= proc(
    funcs::[anything, anything, anything], #`appliable` not inclusive enough.
    part::Partition)::Partition;
    local pair,pos,f,g,h,doIt;
    (f,g,h) := op(funcs);
    #sigh, we don't have a decent 'let', need to use a local proc
    doIt := proc(pair)
    local kb0 := h(condOf(pair));
      Piece( f(condOf(pair), kb0),
             g(valOf(pair), kb0));
    end proc;
    PARTITION(map(doIt,piecesOf(part)));
  end proc,

  Foldr := proc( cons, nil, prt :: Partition, $ )
    foldr(proc(p, x) cons(condOf(p), valOf(p), x); end proc,nil,op(piecesOf(prt)));
  end proc,

  Case := proc(ty,f,g) proc(x) if x::ty then f(x) else g(x) end if end proc end proc,
  Foldr_mb := proc(cons,nil,prt) Case(Partition, x->Foldr(cons,nil,x), x->cons(true,x,nil)) end proc,
  PartitionToPW_mb := Case(Partition, PartitionToPW, x->x),
  PWToPartition_mb := Case(specfunc(piecewise), PWToPartition, x->x),

  PartitionToPW := module()
    export ModuleApply; local pw_cond_ctx;
    ModuleApply := proc(x::Partition, $)
      local parts := piecesOf(x);
        if nops(parts) = 1 and is(op([1,1],parts)) then return op([1,2], parts) end if;
        parts := foldl(pw_cond_ctx, [ [], {} ], op(parts) );
        parts := [seq([condOf(p), valOf(p)][], p=op(1,parts))];
        if op(-2, parts) :: identical(true) then
          parts := subsop(-2=NULL, parts);
      end if;
      piecewise(op(parts));
    end proc;

    pw_cond_ctx := proc(ctx_, p, $)
    local ps, ctx, ctxN, cond, ncond;
      ps, ctx := op(ctx_); cond := condOf(p);
      cond := {extr_conjs(cond)};
      cond := remove(x->x in ctx, cond);
      ncond := `if`(nops(cond)=1
                    , KB:-negate_rel(op(1,cond))
                    , `Not`(bool_And(op(cond))) );
      cond := bool_And(op(cond));
      ctx := ctx union { ncond };
      [ [ op(ps), Piece(cond, valOf(p)) ], ctx ]
    end proc;
  end module,

  isShape := kind ->
  module()
    option record;

    export MakeCtx := proc(p0,_rec)
      local p := p0, pw, p1, wps, ws, vs, cs, w, ps;
      if kind='piecewise' then
        p := Partition:-PWToPartition(p);
      end if;
      w, p1 := Partition:-Simpl:-single_nonzero_piece(p);
      if not w :: identical(true) or p1 <> p then
        [ w, p1 ]
      else
        ps := piecesOf(p);
        wps := map(_rec@valOf, ps);
        ws, vs, cs := map2(op, 1, wps), map2(op, 2, wps), map(condOf, ps);
        if nops(vs) > 0 and
          andmap(v->op(1,vs)=v, vs) and
          ormap(a->a<>{}, ws)
        then
          [ `bool_Or`( op( zip(`bool_And`, ws, cs) ) ) , op(1,vs) ];
        else
          [ true, p0 ];
        end if;
      end if;
    end proc;
    export MapleType := `if`(kind=`PARTITION`,'Partition','specfunc(piecewise)');
  end module,

  # Checks if the given Partition is semantically valid, i.e. the conditions are
  # all disjoint. This exploits the property that if each adjacent pair of
  # conditions is pairwise disjoint, then they are all disjoint
  # (i.e. disjointness is transitive).
  IsValid := proc(p::Partition,$)
    local i, cs; cs := map(condOf, piecesOf(p));
    for i from 2 to nops(cs) do
      if (coulditbe(op(i  ,cs)) assuming op(i-1,cs)) or
         (coulditbe(op(i-1,cs)) assuming op(i  ,cs)) then
        return false; end if;
    end do;
    return true;
  end proc,

  # convert a piecewise to a partition, which is straightforward except:
  # - if any of the branches are unreachable, they are removed
  # - if the last clause is (implicitly) `otherwise`, that clause is filled in
  #     appropriately
  # note that if the piecewise does not cover the entire domain,
  #   then this Partition will be 'invalid' (in the sense that it also
  #   will not cover the entire domain) - the 'correct' thing to do would
  #   probably be to add a new clause whose value is 'undefined'
  # the logic of this function is already essentially implemented, by KB
  # in fact, kb_piecewise does something extremely similar to this
  PWToPartition := proc(x::specfunc(piecewise))::Partition;
    # each clause evaluated under the context so far, which is the conjunction
    # of the negations of all clauses so far
    local ctx := true, n := nops(x), cls := [], cnd, ncnd, i, q, ctxC, cl, p;

    # Checks if the piecewise is valid when translated literally to a Partition
    # if so, that Partition can be returned directly. This is not done by
    # default because the check calls `coulditbe' many times which is
    # potentially much more expensive than just building the Partition from
    # scratch. This should only be used when the piecewise comes from a solver
    # which may or may not already return a 'partition', and when it does return
    # a 'partition', the set of conditions is typically so complicated that
    # rebuilding it produces an unwieldy monster (e.g. SemiAlgebraic in the case
    # of e.g. RoundTrip/t62).
    if 'check_valid' in {_rest} then
      p := Partition(op(x));
      if IsValid(p) then return p end if;
    end if;

    # handles all but the `otherwise` case if there is such a case
    for i in seq(q, q = 1 .. iquo(n, 2)) do
      cnd := op(2*i-1,x); # the clause as given
      # if this clause is unreachable, then every subsequent clause will be as well
      if ctx :: identical(false) then return PARTITION( cls );
      else
        ctxC := `And`(cnd, ctx);              # the condition, along with the context (which is implicit in pw)
        ctxC := Simpl:-condition(ctxC, _rest);

        if cnd :: `=` then ncnd := lhs(cnd) <> rhs(cnd);
        else               ncnd := Not(cnd) end if;

        ctx  := `And`(ncnd, ctx);             # the context for the next clause

        if ctx :: identical(false,[]) then    # this clause is actually unreachable
          return(PARTITION(cls));
        else
          cls := [ op(cls), op(Pieces(ctxC,[op(2*i,x)])) ];
        end if;
      end if;
    end do;

    # if there is an otherwise case, handle that.
    if n::odd then
      ctx := Simpl:-condition(ctx, _rest);
      if not ctx :: identical(false,[]) then
        cls := [ op(cls), op(Pieces(ctx,[op(n,x)])) ];
      end if;
    end if;

    if nops(cls) = 0 then
      WARNING("PWToPartition: the piecewise %1 produced an empty partition", x);
      return 0;
    end if;
    PARTITION( cls );
  end proc,

  # applies a function to the arg if arg::Partition,
  # and if arg::piecewise, then converts the piecewise to a partition,
  # applies the function, then converts back to piecewise
  # this mainly acts as a sanity check
  AppPartOrPw := proc(f,x::Or(Partition,specfunc(piecewise)))
    if x::Partition then f(x);
    else                 PartitionToPW(f(PWToPartition(x))) end if;
  end proc,

  #Check whether the conditions of a Partition satisfy a type (or a proc return
  #truefalse)
  ConditionsSatisfy := proc(P::Partition, test, $)
    local p, ty; ty := `if`(test::type,test,satisfies(test));
    for p in piecesOf(P) do if condOf(p)::ty then return true end if end do;
    false
  end proc,

  #Check whether the conditions of a Partition depend on any of a set of names.
  ConditionsDepend:= proc(P::Partition, V::{name, list(name), set(name)}, $)
    ConditionsSatisfy(P, x->depends(x,V));
  end proc,

  # The cartesian product of two Partitions
  PProd := proc(p0::Partition,p1::Partition,{_add := `+`})::Partition;
  local ps0, ps1, cs, rs, rs0, rs1;
    ps0,ps1 := map(ps -> sort(piecesOf(ps), key=(z->condOf(z))), [p0,p1])[];
    cs := zip(proc(p0,p1)
                if condOf(p0)=condOf(p1) then
                  Piece(condOf(p0),_add(valOf(p0),valOf(p1))) ;
                else [p0,p1];
                end if;
              end proc, ps0,ps1);
    rs, cs := selectremove(c->type(c,list),cs);
    rs0, rs1 := map(k->map(r->op(k,r),rs),[1,2])[];
    rs := map(r0->map(r1-> Piece( bool_And(condOf(r0),condOf(r1)), _add(valOf(r0),valOf(r1)) )
                      ,rs1)[],rs0);
    PARTITION([op(cs),op(rs)]);
  end proc,

  Simpl := module()
    export ModuleApply := proc(p)
      option remember, system;
      local ps, qs, qs1, mk, as; as := _rest;
      if p :: Partition then
        foldr((f,x)->f(x,as), p,
              reduce_branches,
              remove_false_pieces,
              flatten,
              singular_pts);
      elif assigned(distrib_op_Partition[op(0,p)]) then
        mk := distrib_op_Partition[op(0,p)];
        ps := [op(p)];
        ps := map(x->Simpl(x,as), ps);
        ps, qs := selectremove(type, ps, Partition);
        if nops(ps)=0 then return p end if;
        mk(op(qs),foldr(((a,b)->
                         remove_false_pieces(Partition:-PProd(a,b,_add=mk))),
                        op(ps)));
      else
        subsindets(p,{Partition,indices(distrib_op_Partition,nolist)},x->Simpl(x,_rest));
      end if;
    end proc;
    export distrib_op_Partition := table([`+`=`+`,`*`=`*`]);

    export flatten := module()
      export ModuleApply;
      local unpiece, unpart, flatten_with;

      ModuleApply := proc(pr0, { _with := [ 'Partition', unpart ] } )
        local ty, un_ty, pr1, pr2;
        ty, un_ty := op(_with);

        pr1 := subsindets(pr0, ty, un_ty);
        if pr0 <> pr1 then
          ModuleApply(pr1, _with=[ Or('Partiton',`*`), unpart ]);
        else
          pr0
        end if;
      end proc;

      # like Piece, but tries to not be a Piece
      unpiece := proc(c, pr, $)
        flatten_with(proc(mk_q, ps)
                       map(q -> Piece(bool_And(condOf(q),c),mk_q(valOf(q))), ps)[]
                     end proc,
                     x->Piece(c,x),
                     pr);
      end proc;

      unpart := curry(
        flatten_with,proc(mk_q, ps)
                       PARTITION(map(q -> unpiece(condOf(q),valOf(q)), ps))
                     end proc, x->x);

      flatten_with := proc(rec, fail, pr, $)
      local ps, ws;
        if pr :: Partition then
          ps := piecesOf(pr); ws := [];
        elif pr :: `*` then
          ps, ws := selectremove(q->type(q,Partition), [op(pr)]);
          if nops(ps) = 1 then
            ps := piecesOf(op(1,ps));
          else return fail(pr) end if;
        else
          return fail(pr);
        end if;
        rec(x->`*`(op(ws),x), ps);
      end proc;
    end module;

    export single_nonzero_piece_cps := proc(k)
      local r,p; r, p := single_nonzero_piece(_rest);
      if r :: identical(true) then
        args[2]
      else
        k(r, p);
      end if;
    end proc;

    export single_nonzero_piece := proc(e, { _testzero := Testzero })
      local zs, nzs;
      if e :: Partition then
        zs, nzs := selectremove(p -> _testzero(valOf(p)), piecesOf(e));
        if nops(nzs) = 1 then
          return condOf(op(1,nzs)) , valOf(op(1,nzs))
        end if;
      end if;
      true, e
    end proc;

    export remove_false_pieces := proc(e::Partition, kb := KB:-empty)
      PARTITION(remove(p -> type(KB:-assert(condOf(p), kb), t_not_a_kb), piecesOf(e)));
    end proc;

    local `&on` := proc(f,k,$) proc(a,b,$) f(k(a),k(b)) end proc end proc;
    local condition_complexity := proc(x)
      nops(indets(x,PartitionCond)) + nops(indets(x,specfunc({exp, ln})))
    end proc;

    export reduce_branches := proc(e::Partition, kb := KB:-empty, { _testequal := ((a,b) -> Testzero(a-b)) })
      local k, ks, i, vs, ps1, ps; ps := piecesOf(e); vs := map(valOf,ps);
      userinfo(3, :-reduce_branches, printf("Input: %a\n", ps));

      if nops(ps)=1 then return op([1,2],ps); end if;

      # Categorize(group) by equality of piece values
      ps1 := [ListTools:-Categorize(_testequal &on valOf, ps)];
      # unless there are fewer groups than original pieces ...

      ks  := map(nops, ps1); # number of pieces per group

      # build the result
      ps1 := map(p->Piece(bool_Or(condition(bool_Or(map(condOf,p)[]), kb,
                                            'do_solve', 'do_kb', 'do_check')[])
                          ,valOf(op(1,p)))
                 ,ps1);
      userinfo(3, :-reduce_branches, printf("condition: %a\n", ps1));

      # replace the condition of each piece built from many others
      if nops(ps1) < nops(ps) and nops(ps1)>1 then
        for i in select(x->op(1,x)>1,sort(zip(`[]`,ks,[seq(1..nops(ks))]), key=(x->-op(1,x)))) do
          ps1 := piecesOf( replace_piece_cond(PARTITION(ps1), op(2,i)) );
        end do;
      end if;

      return PARTITION(ps1);
    end proc;

    # Replaces a piece (at given index) condition with the logically equivalent
    # one formed from the other pieces.
    export replace_piece_cond := proc(e::Partition, n::integer := -1, failure:=(x->x), cmp_score := [ (x->x), (x->x+1) ], $)
      local p_n, p_n1,ps,cmp; ps := piecesOf(e);
      if abs(n)>nops(ps) then
        error "index out of bound: %1", n;
      elif nops(ps)=1 then
        error "cannot replace in single piece Partition: %1", e
      end if;
      p_n := condOf(op(n, ps));                              # old condition
      p_n1 := Not(bool_Or(map(condOf,subsop(n=NULL,ps))[])); # new condition
      cmp := map(condition_complexity, [p_n1, p_n]);

      # a cheap metric for determining if the new condition is an improvement
      if `<=`(zip(apply, cmp_score, cmp)[]) then
        ps := subsop([n,1]=p_n1, ps);
        PARTITION(ps);
      else
        failure(PARTITION(ps));
      end if;
    end proc;

    # Removal of singular points from partitions
    # works with other things too!
    export singular_pts := module()
      local t_constant := (ns->x->(indets(x,And(name,Not(constant))) minus ns)={});
      local can_remove := proc(ns)
        local t1, t2;
        t1 := satisfies(t_constant(ns));
        t2 := satisfies(n->n in ns);
        'Or'(`=`(t2,{t1,t2}),`=`(t1,t2));
      end proc;

      local weakening := {`<=`=`<`, `>=`=`>`};
      local can_replace := proc(ns)
        local t := satisfies(n->n in ns);
        'And'('specfunc'(map(lhs,weakening)),
              {'anyfunc'('anything',t),'anyfunc'(t,'anything')});
      end proc;
      local do_replace := proc(c)
        table([op(weakening)])[op(0,c)](op(c));
      end proc;

      export ModuleApply := proc(sh, kb::t_kb:=KB:-empty,{_name_cands::list := [] })
        local ns, sh1; sh1 := sh;
        # todo: work with array types as well?
        ns := select(type, [op(kb)], And(KB:-t_kb_Introduce,anyfunc(anything,specfunc({`AlmostEveryReal`,`HReal`}))));
        ns := map(curry(op,1), ns);
        ns := { op(ns), op(_name_cands) };
        if ns={} then return sh end if;

        sh1 := subsindets(sh1, can_remove(ns), _->false);
        sh1 := eval(eval(sh1, [`And`=bool_And,`Or`=bool_Or]));
        sh1 := subsindets(sh1, 'specfunc'('specfunc'(map(op,weakening)),Not), bool_Not@op);
        sh1 := subsindets(sh1, can_replace(ns), do_replace);
        subsindets[flat](sh1, Partition, pr->remove_false_pieces(pr,kb));
      end proc;
    end module; # singular_pts

    export condition := module()
      local is_extra_sol := x -> (x :: `=` and rhs(x)=lhs(x) and lhs(x) :: name);
      local postproc_for_solve := proc(ctx, ctxSlv)
                               ::{identical(false), list({boolean,relation,specfunc(boolean,And),`and`(boolean)})};
        local ctxC := ctxSlv;
        if ctxC = [] then
          ctxC := [] ;
        elif nops(ctxC)> 1 then
          ctxC := map(x -> postproc_for_solve(ctx, [x], _rest)[], ctxC);
        elif nops(ctxC) = 1 then
          ctxC := op(1,ctxC);
          if ctxC :: set then
            if ctxC :: identical('{}') then
              ctxC := NULL;
            else
              ctxC := remove(is_extra_sol, ctxC);
               # if all the solutions are 'extra', the solution is actually just
               # garbage. Maple can't really tell and doesn't just return the
               # empty set (no solutions) for these cases.
              if ctxC = {} then
                ctxC := ctx;
              else
                ctxC := bool_And(op(ctxC));
              end if;
            end if ;
            ctxC := [ctxC];
          elif ctxC :: specfunc('piecewise') then
            ctxC := PWToPartition(ctxC, _rest);
            ctxC := [ seq( map( o -> condOf(c) and o
                                , postproc_for_solve(ctx, valOf(c), _rest))[]
                           , c=piecesOf(ctxC) )] ;
          else
            ctxC := FAIL;
          end if;
        else
          ctxC := FAIL;
        end if;
        if ctxC = FAIL then
          error "don't know what to do with %1", ctxSlv;
        else
          ctxC;
        end if;
      end proc;

      # For some reason, solve just disregards these sorts of conditions
      # altogether, but not when they appear on their own! e.g.
      #  solve( {a<>b} )       = {a=a,a<>b}
      #  solve( {Not(a<>b)} )  = {a=a,b=b}  -- but should be {..,a=b}
      local can_solve := proc(c,$)
        local neq_nn := `<>`(name,name);
        evalb(indets(c, neq_nn) = {} or not has(c,`idx`))
      end proc;

      export ModuleApply := proc(ctx, kb := KB:-empty)::list(PartitionCond);
        option remember, system;
        local ctxC, ctxC1, ctxC_c, ctxC1_c;
        ctxC := ctx;
        if ctx :: identical(true) then
          error "Simpl:-condition: don't know what to do with %1", ctxC;
        end if;
        if 'do_kb' in {_rest} then
          ctxC1 := KB:-kb_subtract( KB:-assert( ctxC, kb ), kb );
          if nops(ctxC1)=1 and op([1,1], ctxC1)=KB:-assert then
            ctxC1 := op([1,2], ctxC1);
            ctxC1_c, ctxC_c := map(condition_complexity, [ctxC1,ctxC])[];
            if ctxC1_c < ctxC_c then
              ctxC := ctxC1;
            end if;
          end if;
        end if;
        if condition_complexity(ctxC)=1 then
          return [ctxC];
        end if;

        ctxC := KB:-chill(ctxC);

        if 'do_solve' in {_rest} and _Env_HakaruSolve<>false and can_solve(ctxC) then
          ctxC1 := solve({ctxC}, 'useassumptions'=true);
          if ctxC1 = ctxC then
            # sometimes solve returns unevaluated which confuses postproc because
            # it expects the typical output of solve
            ctxC := [ctxC];
          elif ctxC1 = NULL and indets(ctx, specfunc(`exp`)) <> {} then
            ctxC := [ctxC];
          else
            ctxC1 := postproc_for_solve(ctxC, [ctxC1], _rest);
            if 'do_check' in {_rest} and condition_complexity(ctxC)>condition_complexity(ctxC1) then
              ctxC := ctxC1;
            end if;
          end if;
          if indets(ctxC, specfunc({`Or`, `or`})) <> {} then
            userinfo(10, 'Simpl:-condition',
                     printf("output: \n"
                            "  %a\n\n"
                            , ctxC ));
          end if;
        else
          ctxC1 := ctxC;
          ctxC := [seq(Domain:-simpl_relation(ctxC1, norty=t), t=['DNF','CNF'])];
          ctxC := eval(ctxC,`And`=bool_And);
          ctxC := op(1, sort(ctxC, key=condition_complexity));
          if ctxC :: specfunc(`Or`) then
            ctxC := [op(ctxC)]
          else
            ctxC := [ctxC];
          end if;
        end if;
        if 'no_split_disj' in {_rest} then
          ctxC := [ bool_Or(op(ctxC)) ];
        end if;
        ctxC := KB:-warm(ctxC);
        `if`(ctxC::list, ctxC, [ctxC]);
      end proc;
    end module; #Simpl:-condition
  end module, #Simpl

  SamePartition := proc(eqCond, eqPart, p0 :: Partition, p1 :: Partition, $)
    local ps0, ps1, pc0, the;
    ps0, ps1 := map(piecesOf,[p0,p1])[];
    if nops(ps0) <> nops(ps1) then return false end if;
    for pc0 in ps0 do
      the, ps1 :=
        selectremove(pc1 ->
          eqCond( condOf(pc1), condOf(pc0) ) and
          eqPart( valOf(pc1) , valOf(pc0)  )     ,ps1);
      if nops(the) <> 1 then
        return false;
      end if;
    end do;
    true;
  end proc
;
  uses Hakaru;
  ModuleLoad();
end module:


Fix a bug in graft that causes calling op with no-longer-valid index

# Teach Maple (through depends and eval) about our new binding forms.
# forall bind from 1st arg to 2nd arg.
# Ints,Sums,ints,sums bind from 2nd arg to 1st arg, and also from each element
#   of the 4th arg to the other elements on the left and to the 3rd arg.

`depends/forall` := proc(bvar, pred, x, $)
  depends(pred, x minus convert(bvar, 'set'))
end proc:

`depends/Ints` := proc(body, bvar, rng, loops, x, y, $)
  local xx, i;
  if nargs = 5 then
    xx := x; # y is ununsed and x lists the variables to look for
  else
    xx := y; # x is some KB and y lists the variables to look for
    if depends(x, y) then return true end if;
  end if;
  # don't remove bvar from xx!
  if depends(body, xx minus {bvar}) then return true end if;
  for i from nops(loops) to 1 by -1 do
    if depends(op([i,2],loops), xx) then return true end if;
    xx := xx minus {op([i,1],loops)};
  end do;
  depends(rng, xx)
end proc:
`depends/Sums` := eval(`depends/Ints`):
`depends/ints` := eval(`depends/Ints`):
`depends/sums` := eval(`depends/Ints`):

`eval/forall` := proc(e, eqs, $)
  local bvar, pred;
  bvar, pred := op(e);
  eval(op(0,e), eqs)(BindingTools:-generic_evalat(bvar, pred, eqs))
end proc:

`eval/Ints` := proc(e, eqs, $)
  local body, bvar, rng, loops, n, i;
  body, bvar, rng, loops := op(1..4, e);
  bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
  eval(op(0,e), eqs)(body, bvar,
                     BindingTools:-generic_evalatstar(rng, loops, eqs),
                     op(5..-1,e))
end proc:
`eval/Sums` := eval(`eval/Ints`):
`eval/ints` := eval(`eval/Ints`):
`eval/sums` := eval(`eval/Ints`):

`eval/Int` := proc(e, eqs, $)
  local body, bound, bvar;
  body, bound := op(1..2, e);
  if bound :: name then
    bound, body := BindingTools:-generic_evalat(bound, body, eqs);
  elif bound :: `=` then
    bvar := lhs(bound);
    bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
    bound := bvar = eval(rhs(bound), eqs);
  else
    body, bound := BindingTools:-generic_evalatstar(body, bound, eqs);
  end if;
  eval(op(0,e), eqs)(body, bound, op(eval([op(3..-1,e)], eqs)))
end proc:
`eval/Sum`     := eval(`eval/Int`):
`eval/Product` := eval(`eval/Int`):
`eval/int`     := eval(`eval/Int`):
`eval/sum`     := eval(`eval/Int`):
`eval/product` := eval(`eval/Int`):

#############################################################################

Loop := module ()
  option package;
  local intssums, enter_piecewise, wrap,
        Binder, Stmt, t_binder, t_stmt, t_exp,
        ModuleLoad;
  export
     # These first few are smart constructors (for themselves):
         ints, sums,
     # while these are "proper functions"
         mk_HArray, genLoop, unproducts, unproduct,
         peel, split, graft, rebase_lower, rebase_upper;
  # these names are not assigned (and should not be).  But they are
  # used as global names, so document that here.
  global Ints, Sums, csgn;
  uses Hakaru, KB;

  t_binder := 'Binder(identical(product, Product, sum, Sum), t_kb)';
  t_stmt   := 'Stmt(anything, list, list)';
  t_exp    := '{Stmt(identical(exp), [], []),
                Stmt(identical(`^`), [anything], [])}';

  ints := proc() intssums('ints', 'int', _passed) end proc;
  sums := proc() intssums('sums', 'sum', _passed) end proc;

  intssums := proc(makes::name, make::name,
                   ee::anything, xx::name, rr::range, ll::list(name=range),
                   kb::t_kb:=empty, $)
    local t, x, e, r, l, kb1, w0, pp;
    t := `if`(make=int, HReal(open_bounds(rr)), HInt(closed_bounds(rr)));
    x, kb1 := genType(xx, mk_HArray(t, ll), kb);
    e := eval(ee, xx=x);
    if nops(ll) > 0 then
      kb1 := assert(size(x)=op([-1,2,2],ll)-op([-1,2,1],ll)+1, kb1);
    end if;
    e := simplify_assuming(e, kb1);
    r, l, kb1 := genLoop(rr, ll, kb, 'Integrand'(x,e));
    w0, pp := unproducts(e, x, l, kb1);
    if depends(w0, x) then
      'makes'(e, x, rr, ll)
    else
      w0 * foldl(''product'', 'make'(pp,x=r), op(l))
    end if
  end proc;

  mk_HArray := proc(t::t_type, loops::list(name=range), $)
    local res, i;
    res := t;
    for i in loops do res := HArray(res) end do;
    res
  end proc;

  genLoop := proc(e, loops::list(name=range), kb::t_kb)
    local kb1, rng, ind, do_subst, i;
    kb1 := kb;
    rng := table();
    ind := table();
    do_subst := e -> foldl(((e,eq) -> eval(e, op([lhs(eq),1],loops)=rhs(eq))),
                           e, entries(ind, 'pairs'));
    for i from nops(loops) to 1 by -1 do
      rng[i] := do_subst(op([i,2],loops));
      ind[i], kb1 := genType(op([i,1],loops), HInt(closed_bounds(rng[i])),
                               kb1, _rest);
    end do;
    do_subst(e), zip(`=`, [entries(ind, 'nolist')],
                          [entries(rng, 'nolist')]), kb1
  end proc;

  unproducts := proc(w, x::name, loops::list(name=range), kb::t_kb, $)
    local w0, pp, j, w1, w2, loop;
    w0 := 1;
    pp := w;
    for j from nops(loops) to 1 by -1 do
      w1, pp := op(unproduct(pp, x, op(j,loops), [], `*`, kb, kb));
      # separate out each of the factors in w1, as they might have different
      # variable dependencies, which can be exploited by other routines
      w2 := convert(w1, 'list', '`*`');
      for loop in [op(j+1..-1, loops)] do
        w2 := map((w -> product(eval(w, x=idx(x,lhs(loop))), loop)), w2);
      end do;
      w0 := w0 * `*`(op(w2));
      # w0 := w0 * foldl(product, w1, op(j+1..-1, loops));
    end do;
    # Rewrite ... * piecewise(i<=kk-1, xs^2, 1)
    #      to ... * xs ^ (2*piecewise(i<=kk-1, 1))
    # because the latter is easier to integrate and recognize with respect to xs
    pp := maptype(`*`,
      proc (p)
        local n, s, r;
        if p :: 'And(specfunc(piecewise), anyfunc(freeof(x), anything, 1))' then
          n := indets(op(1,p),name);
          if op(2,p) :: {'exp(anything)', '`^`'('freeof'(n),'anything')} then
            s, r := selectremove(depends, convert(op([2,-1],p),'list','`*`'), n);
            subsop(-1 = `*`(piecewise(op(1,p), `*`(op(s))), op(r)), op(2,p))
          else
            s, r := selectremove(depends, convert(op(2,p),'list','`*`'), n);
            `*`(op(r)) ^ piecewise(op(1,p), 1)
              * `if`(nops(s) > 0, piecewise(op(1,p), `*`(op(s)), 1), 1)
          end if
        else
          p
        end if
      end proc,
      pp);
    w0, pp
  end proc;

  # Find [w1,pp] so that
  #   wrap(heap,w,mode,kb1,kb0)
  #   = w1*product(eval(pp,var=idx(var,lhs(loop))),loop)
  # making w1 depend on var as little as possible.
  # The flag "mode" should be `+` if "heap" contains an entry of the form
  # t_exp, or `*` otherwise.
  unproduct := proc(w, var::name, loop::(name=range),
                    heap::list, mode::identical(`*`,`+`),
                    kb1::t_kb, kb0::t_kb, $)
    local ind, res, dummy, kb, kbThen, i, w1, pp, s, r, x;
    if not depends(w, var) then
      return [wrap(heap, w, mode, kb1, kb0), 1]
    end if;
    ind := map2(op, 2, indets(w, idx(identical(var), anything)));
    if nops(ind) = 1 then
      ind := op(ind);
      # Make sure ind contains no bound variables before lifting it!
      # So, check that "extract using indets" and "rename using eval" commute.
      s := indets(ind, 'name');
      s := map(proc(x,$) local y; `if`(depends(ind,x), x=y, NULL) end proc, s);
      if indets(eval(w, s), idx(identical(var), anything))
                = {idx(var, eval(ind, s))} then
        kb  := assert(lhs(loop)=ind, kb1); # BUG! bijectivity assumed!
        res := subs(idx(var,ind) = idx(var,lhs(loop)), w);
        res := wrap(heap, res, mode, kb, kb0);
        res := subs(idx(var,lhs(loop))=dummy, res);
        if not depends(res, var) then
          return [1, subs(dummy=var, res)]
        end if
      end if
    end if;
    if w :: mode then
      res := map(unproduct, `if`(mode=`*`, list_of_mul(w,kb1), [op(w)]),
                 var, loop, heap, mode, kb1, kb0);
      return [`*`(op(map2(op,1,res))), `*`(op(map2(op,2,res)))]
    end if;
    if w :: 'specfunc(piecewise)' then
      kb := kb1;
      for i from 1 to nops(w) do
        if i :: even then
          kbThen := assert(    op(i-1,w) , kb);
          kb     := assert(Not(op(i-1,w)), kb);
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kbThen,kb0))
        elif i = nops(w) then
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kb    ,kb0))
        end if
      end do;
      return [`*`(entries(w1,'nolist')), `*`(entries(pp,'nolist'))]
    end if;
    if mode = `*` then
      if w :: (anything^freeof(var)) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(`^`, [], [op(2,w)])], `*`, kb1, kb0)
      elif w :: exp(anything) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(exp, [], [])], `+`, kb1, kb0)
      elif w :: (freeof(var)^anything) then
        return unproduct(op(2,w), var, loop,
                         [op(heap), Stmt(`^`, [op(1,w)], [])], `+`, kb1, kb0)
      end if
    end if;
    if mode = `+` and w :: `*` then
      s, r := selectremove(depends, w, var);
      if s :: `*` then
        # Nonlinear %1 (time to reread kiselyov-lifted?)
      else
        return unproduct(s, var, loop,
                         [op(heap), Stmt(`*`, [], [r])], `+`, kb1, kb0)
      end if
    end if;
    if w :: And(specfunc(`if`(mode = `*`, {product, Product}, {sum, Sum})),
                anyfunc(anything, name=range(freeof(var)))) then
      x, kb := genType(op([2,1],w),
                       HInt(Bound(`>=`,op([2,2,1],w)),
                            Bound(`<=`,op([2,2,2],w))),
                       kb1,
                       w, var, loop, heap);
      return unproduct(eval(op(1,w), op([2,1],w)=x), var, loop,
                       [op(heap), Binder(op(0,w), kb1)], mode, kb, kb0)
    end if;
    if mode = `*` and w :: '{`+`, specfunc({sum, Sum})}' then
      # Maybe this w is one of those big sums involving products that are
      # always equal to 1, left behind by the density of Categorical
      w1 := graft(split(peel(lift_piecewise(w))));
      w1 := combine(rebase_upper(w1));
      w1 := combine(rebase_lower(w1));
      return [wrap(heap, w1, mode, kb1, kb0), 1]
    end if;
    return [wrap(heap, w, mode, kb1, kb0), 1]
  end proc;

  enter_piecewise := proc(ee, kb0::t_kb, mode::identical(`*`,`+`), $)
    local e, kb, mo;
    e  := ee;
    kb := kb0;
    mo := mode();
    while e :: 'specfunc(piecewise)' and nops(e) = 3 do
      if op(3,e) = mo then
        kb := assert(op(1,e), kb);
        e := op(2,e);
      elif op(2,e) = mo then
        kb := assert(Not(op(1,e)), kb);
        e := op(3,e);
      else
        break;
      end if;
    end do;
    e, kb
  end proc;

  wrap := proc(heap::list, e1, mode1::identical(`*`,`+`),
               kb1::t_kb, kb0::t_kb, $)
    local e, kb, mode, i, entry, rest, var, new_rng, make,
       dom_spec, w, arrrgs;
    e    := e1;
    kb   := kb1;
    mode := mode1;
    for i from nops(heap) to 1 by -1 do
      entry := op(i,heap);
      if entry :: t_binder then
        if not (op(1,entry) in `if`(mode=`+`, {sum,Sum},
                                              {product,Product})) then
          print("Warning: heap mode inconsistency", heap, mode1)
        end if;
        e := simplify_assuming(e, op(2,entry));
        e, kb := enter_piecewise(e, kb, mode);
        rest := kb_subtract(kb, op(2,entry));
        new_rng, rest := selectremove(type, rest,
          {[identical(genType), name, specfunc(HInt)],
           [identical(genLet), name, anything]});
        if not (new_rng :: [list]) then
          error "kb_subtract should return exactly one gen*"
        end if;
        new_rng := op(new_rng);
        var     := op(2,new_rng);
        if op(1,new_rng) = genType then
          make    := op(1,entry);
          new_rng := range_of_HInt(op(3,new_rng));
        else # op(1,new_rng) = genLet
          make    := eval;
          new_rng := op(3,new_rng);
        end if;
        dom_spec, rest := selectremove(depends,
          map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest),
          var);
        (e, w) := selectremove(depends, convert(e, 'list', `*`), var);
        w := `*`(op(w));
        if mode = `*` and not (w = 1) then
          w := w ^ `if`(make=eval,eval,sum)
                       (piecewise_And(dom_spec, 1, 0), var=new_rng);
        end if;
        e := w * make(piecewise_And(dom_spec, `*`(op(e)), mode()), var=new_rng);
        kb := foldr(assert, op(2,entry), op(rest));
      elif entry :: t_stmt then
        # We evaluate arrrgs first, in case op(1,stmt) is an operation (such as
        # piecewise) that looks ahead at how many arguments it is passed before
        # they are evaluated.
        arrrgs := op(op(2,entry)), e, op(op(3,entry));
        e      := op(1,entry)(arrrgs);
        if entry :: t_exp then
          if mode <> `+` then
            print("Warning: heap mode inconsistency?", heap, mode1)
          end if;
          mode := `*`;
        end if
      else error "Malformed heap entry %1", entry end if
    end do;
    if mode <> `*` then
      print("Warning: heap mode inconsistency??", heap, mode1)
    end if;
    e, kb := enter_piecewise(e, kb, mode);
    rest := kb_subtract(kb, kb0);
    rest := map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest);
    piecewise_And(rest,e,mode())
  end proc;

  # Rewrite product(piecewise(i+42=lo+42,th,el),i=lo..hi)
  # to eval(th,i=lo)*product(el,i=lo+1..hi)
  peel := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(specfunc(piecewise), name=range))',
    proc(e, $)
      local body, x, r, line, test, make, here, rest, res;
      body := op(1,e);
      if not (1<nops(body) and op(1,body)::{`=`,`<`,`<=`}) then return e end if;
      x, r := op(op(2,e));
      line := op([1,1],body) - op([1,2],body);
      if 1 = degree(line, x) then
        if op(1,body) :: `=`  then
          test := proc (y,z,$)
            if Testzero(eval(line, x=y)) then true
            else FAIL end if
          end proc;
        elif op(1,body) :: `<` then
          test := proc (y,z,$)
            local l;
            l := [eval(line, x=y), eval(line, x=z)];
            if   l :: [negative, nonnegative] then true
            elif l :: [nonnegative, negative] then false
            else FAIL end if
          end proc;
        elif op(1,body) :: `<=` then
          test := proc (y,z,$)
            local l;
            l := [eval(line, x=y), eval(line, x=z)];
            if   l :: [nonpositive, positive] then true
            elif l :: [positive, nonpositive] then false
            else FAIL end if
          end proc;
        end if;
        if op(0,e) in {sum,Sum} then
          make := `+`;
        elif op(0,e) in {product,Product} then
          make := `*`;
        end if;
        here := op(2,body);
        if nops(body)=2 then
          rest := 0;
        elif nops(body)=3 then
          rest := op(3,body);
        elif {op([1,0],body) , op([3,0],body)} = {`<`, `<=`}
          and op([1,1],body) = op([3,2],body)
          and op([1,2],body) = op([3,1],body) then
          rest := op(4,body);
        else
          rest := subsop(1=NULL,2=NULL,body);
        end if;
        res := test(lhs(r), lhs(r)+1);
        if res <> FAIL then
          return make(eval(`if`(res, here, rest), x=lhs(r)),
                      subsop(1 = `if`(res, rest, here), [2,2,1]=lhs(r)+1, e));
        end if;
        res := test(rhs(r), rhs(r)-1);
        if res <> FAIL then
          return make(eval(`if`(res, here, rest), x=rhs(r)),
                      subsop(1 = `if`(res, rest, here), [2,2,2]=rhs(r)-1, e));
        end if;
      end if;
      e
    end proc);
  end proc:

  # Expand sum(a*(b-c),q) to sum(a*b,q)-sum(a*c,q)
  split := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum}),
                        anyfunc(And(`*`,Not(`*`(Not(`+`)))),name=anything))',
    proc(e, $)
      local terms, x;
      terms := convert(expand(op(1,e), op(indets(op(1,e), function))),
                       'list', `+`);
      x := op([2,1],e);
      `+`(op(map(proc(term, $)
        local s, r;
        s, r := selectremove(depends, convert(term, 'list', `*`), x);
        `*`(op(r), subsop(1=`*`(op(s)),e))
      end proc, terms)))
    end proc)
  end proc:

  # Simplify f(lo-1)*product(f(i),i=lo..hi) to product(f(i),i=lo-1..hi)
  graft := proc(ee, $)
    subsindets(ee, 'Or(And(`*`,Not(`*`(Not(specfunc({product,Product}))))),
                       And(`+`,Not(`+`(Not(specfunc({sum    ,Sum    }))))))',
    proc(e, $)
      local produce, factors, i, j;
      produce := `if`(e::`*`, '{product,Product}',
                              '{sum    ,Sum    }');
      factors := sort(convert(e,'list'),
                      key = (factor -> -numboccur(factor,produce)));
      for i from nops(factors) to 2 by -1 do
        for j from i-1 to 1 by -1 do
          if op(j,factors) :: 'And'('specfunc'(produce),
                                    'anyfunc(anything,name=range)') then
            if Testzero(op(i,factors) - eval(op([j,1],factors),
                 op([j,2,1],factors)=op([j,2,2,1],factors)-1)) then
              factors := subsop(i=NULL,applyop(`-`,[j,2,2,1],factors,1));
              break
            elif Testzero(op(i,factors) - eval(op([j,1],factors),
                   op([j,2,1],factors)=op([j,2,2,2],factors)+1)) then
              factors := subsop(i=NULL,applyop(`+`,[j,2,2,2],factors,1));
              break
            end if
          end if
        end do
      end do;
      op(0,e)(op(factors))
    end proc)
  end proc:

  # Normalize sum(f(i),i=2..hi) to sum(f(i+2),i=0..hi-2)
  rebase_lower := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,
                          name=Not({0,SymbolicInfinity,undefined})..anything))',
    proc(e, $)
      subsop([2,2,1]=0,
             applyop(`-`,
                     [2,2,2],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,1],e)),
                     op([2,2,1],e)))
    end proc)
  end proc:

  # Normalize sum(f(i),i=lo..2) to sum(f(i+2),i=lo-2..0)
  rebase_upper := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,
                          name=anything..Not({0,SymbolicInfinity,undefined})))',
    proc(e, $)
      subsop([2,2,2]=0,
             applyop(`-`,
                     [2,2,1],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,2],e)),
                     op([2,2,2],e)))
    end proc)
  end proc:

  ModuleLoad := proc($)
    # Override csgn to work a little bit harder on piecewise and sum
    # (to get rid of csgn(1/2+1/2*sum(piecewise(...,1,0),...))
    #  produced by int on a Gaussian mixture model)
    unprotect(csgn);
    csgn := overload([
      # Handle if the csgn of a piecewise doesn't depend on which branch
      proc(a :: specfunc(piecewise), $)
        option overload;
        local r, i;
        r := {seq(`if`(i::even or i=nops(a), csgn(op(i,a)), NULL),
                  i=1..nops(a))};
        if nops(r)=1 then return op(r) end if;
        if not assigned(_Envsignum0) then
          r := r minus {0};
          if nops(r)=1 then return op(r) end if;
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      # Handle if the csgn of a sum doesn't depend on the bound variable
      proc(a :: And(specfunc({sum, Sum}), anyfunc(anything, name=range)), $)
        option overload;
        local r;
        r := csgn(op(1,a));
        if not depends(r,op([2,1],a)) then
          return signum(op([2,2,2],a)+1-op([2,2,1],a)) * r
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      csgn]);
    protect(csgn);
  end proc;

  ModuleLoad();

end module; # Loop

# Teach Maple (through depends and eval) about our new binding forms.
# forall bind from 1st arg to 2nd arg.
# Ints,Sums,ints,sums bind from 2nd arg to 1st arg, and also from each element
#   of the 4th arg to the other elements on the left and to the 3rd arg.

`depends/forall` := proc(bvar, pred, x, $)
  depends(pred, x minus convert(bvar, 'set'))
end proc:

`depends/Ints` := proc(body, bvar, rng, loops, x, y, $)
  local xx, i;
  if nargs = 5 then
    xx := x; # y is ununsed and x lists the variables to look for
  else
    xx := y; # x is some KB and y lists the variables to look for
    if depends(x, y) then return true end if;
  end if;
  # don't remove bvar from xx!
  if depends(body, xx minus {bvar}) then return true end if;
  for i from nops(loops) to 1 by -1 do
    if depends(op([i,2],loops), xx) then return true end if;
    xx := xx minus {op([i,1],loops)};
  end do;
  depends(rng, xx)
end proc:
`depends/Sums` := eval(`depends/Ints`):
`depends/ints` := eval(`depends/Ints`):
`depends/sums` := eval(`depends/Ints`):

`eval/forall` := proc(e, eqs, $)
  local bvar, pred;
  bvar, pred := op(e);
  eval(op(0,e), eqs)(BindingTools:-generic_evalat(bvar, pred, eqs))
end proc:

`eval/Ints` := proc(e, eqs, $)
  local body, bvar, rng, loops, n, i;
  body, bvar, rng, loops := op(1..4, e);
  bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
  eval(op(0,e), eqs)(body, bvar,
                     BindingTools:-generic_evalatstar(rng, loops, eqs),
                     op(5..-1,e))
end proc:
`eval/Sums` := eval(`eval/Ints`):
`eval/ints` := eval(`eval/Ints`):
`eval/sums` := eval(`eval/Ints`):

`eval/Int` := proc(e, eqs, $)
  local body, bound, bvar;
  body, bound := op(1..2, e);
  if bound :: name then
    bound, body := BindingTools:-generic_evalat(bound, body, eqs);
  elif bound :: `=` then
    bvar := lhs(bound);
    bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
    bound := bvar = eval(rhs(bound), eqs);
  else
    body, bound := BindingTools:-generic_evalatstar(body, bound, eqs);
  end if;
  eval(op(0,e), eqs)(body, bound, op(eval([op(3..-1,e)], eqs)))
end proc:
`eval/Sum`     := eval(`eval/Int`):
`eval/Product` := eval(`eval/Int`):
`eval/int`     := eval(`eval/Int`):
`eval/sum`     := eval(`eval/Int`):
`eval/product` := eval(`eval/Int`):

#############################################################################

Loop := module ()
  option package;
  local intssums, enter_piecewise, wrap,
        Binder, Stmt, t_binder, t_stmt, t_exp,
        ModuleLoad;
  export
     # These first few are smart constructors (for themselves):
         ints, sums,
     # while these are "proper functions"
         mk_HArray, genLoop, unproducts, unproduct,
         peel, split, graft, rebase_lower, rebase_upper;
  # these names are not assigned (and should not be).  But they are
  # used as global names, so document that here.
  global Ints, Sums, csgn;
  uses Hakaru, KB;

  t_binder := 'Binder(identical(product, Product, sum, Sum), t_kb)';
  t_stmt   := 'Stmt(anything, list, list)';
  t_exp    := '{Stmt(identical(exp), [], []),
                Stmt(identical(`^`), [anything], [])}';

  ints := proc() intssums('ints', 'int', _passed) end proc;
  sums := proc() intssums('sums', 'sum', _passed) end proc;

  intssums := proc(makes::name, make::name,
                   ee::anything, xx::name, rr::range, ll::list(name=range),
                   kb::t_kb:=empty, $)
    local t, x, e, r, l, kb1, w0, pp;
    t := `if`(make=int, HReal(open_bounds(rr)), HInt(closed_bounds(rr)));
    x, kb1 := genType(xx, mk_HArray(t, ll), kb);
    e := eval(ee, xx=x);
    if nops(ll) > 0 then
      kb1 := assert(size(x)=op([-1,2,2],ll)-op([-1,2,1],ll)+1, kb1);
    end if;
    e := simplify_assuming(e, kb1);
    r, l, kb1 := genLoop(rr, ll, kb, 'Integrand'(x,e));
    w0, pp := unproducts(e, x, l, kb1);
    if depends(w0, x) then
      'makes'(e, x, rr, ll)
    else
      w0 * foldl(''product'', 'make'(pp,x=r), op(l))
    end if
  end proc;

  mk_HArray := proc(t::t_type, loops::list(name=range), $)
    local res, i;
    res := t;
    for i in loops do res := HArray(res) end do;
    res
  end proc;

  genLoop := proc(e, loops::list(name=range), kb::t_kb)
    local kb1, rng, ind, do_subst, i;
    kb1 := kb;
    rng := table();
    ind := table();
    do_subst := e -> foldl(((e,eq) -> eval(e, op([lhs(eq),1],loops)=rhs(eq))),
                           e, entries(ind, 'pairs'));
    for i from nops(loops) to 1 by -1 do
      rng[i] := do_subst(op([i,2],loops));
      ind[i], kb1 := genType(op([i,1],loops), HInt(closed_bounds(rng[i])),
                               kb1, _rest);
    end do;
    do_subst(e), zip(`=`, [entries(ind, 'nolist')],
                          [entries(rng, 'nolist')]), kb1
  end proc;

  unproducts := proc(w, x::name, loops::list(name=range), kb::t_kb, $)
    local w0, pp, j, w1, w2, loop;
    w0 := 1;
    pp := w;
    for j from nops(loops) to 1 by -1 do
      w1, pp := op(unproduct(pp, x, op(j,loops), [], `*`, kb, kb));
      # separate out each of the factors in w1, as they might have different
      # variable dependencies, which can be exploited by other routines
      w2 := convert(w1, 'list', '`*`');
      for loop in [op(j+1..-1, loops)] do
        w2 := map((w -> product(eval(w, x=idx(x,lhs(loop))), loop)), w2);
      end do;
      w0 := w0 * `*`(op(w2));
      # w0 := w0 * foldl(product, w1, op(j+1..-1, loops));
    end do;
    # Rewrite ... * piecewise(i<=kk-1, xs^2, 1)
    #      to ... * xs ^ (2*piecewise(i<=kk-1, 1))
    # because the latter is easier to integrate and recognize with respect to xs
    pp := maptype(`*`,
      proc (p)
        local n, s, r;
        if p :: 'And(specfunc(piecewise), anyfunc(freeof(x), anything, 1))' then
          n := indets(op(1,p),name);
          if op(2,p) :: {'exp(anything)', '`^`'('freeof'(n),'anything')} then
            s, r := selectremove(depends, convert(op([2,-1],p),'list','`*`'), n);
            subsop(-1 = `*`(piecewise(op(1,p), `*`(op(s))), op(r)), op(2,p))
          else
            s, r := selectremove(depends, convert(op(2,p),'list','`*`'), n);
            `*`(op(r)) ^ piecewise(op(1,p), 1)
              * `if`(nops(s) > 0, piecewise(op(1,p), `*`(op(s)), 1), 1)
          end if
        else
          p
        end if
      end proc,
      pp);
    w0, pp
  end proc;

  # Find [w1,pp] so that
  #   wrap(heap,w,mode,kb1,kb0)
  #   = w1*product(eval(pp,var=idx(var,lhs(loop))),loop)
  # making w1 depend on var as little as possible.
  # The flag "mode" should be `+` if "heap" contains an entry of the form
  # t_exp, or `*` otherwise.
  unproduct := proc(w, var::name, loop::(name=range),
                    heap::list, mode::identical(`*`,`+`),
                    kb1::t_kb, kb0::t_kb, $)
    local ind, res, dummy, kb, kbThen, i, w1, pp, s, r, x;
    if not depends(w, var) then
      return [wrap(heap, w, mode, kb1, kb0), 1]
    end if;
    ind := map2(op, 2, indets(w, idx(identical(var), anything)));
    if nops(ind) = 1 then
      ind := op(ind);
      # Make sure ind contains no bound variables before lifting it!
      # So, check that "extract using indets" and "rename using eval" commute.
      s := indets(ind, 'name');
      s := map(proc(x,$) local y; `if`(depends(ind,x), x=y, NULL) end proc, s);
      if indets(eval(w, s), idx(identical(var), anything))
                = {idx(var, eval(ind, s))} then
        kb  := assert(lhs(loop)=ind, kb1); # BUG! bijectivity assumed!
        res := subs(idx(var,ind) = idx(var,lhs(loop)), w);
        res := wrap(heap, res, mode, kb, kb0);
        res := subs(idx(var,lhs(loop))=dummy, res);
        if not depends(res, var) then
          return [1, subs(dummy=var, res)]
        end if
      end if
    end if;
    if w :: mode then
      res := map(unproduct, `if`(mode=`*`, list_of_mul(w,kb1), [op(w)]),
                 var, loop, heap, mode, kb1, kb0);
      return [`*`(op(map2(op,1,res))), `*`(op(map2(op,2,res)))]
    end if;
    if w :: 'specfunc(piecewise)' then
      kb := kb1;
      for i from 1 to nops(w) do
        if i :: even then
          kbThen := assert(    op(i-1,w) , kb);
          kb     := assert(Not(op(i-1,w)), kb);
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kbThen,kb0))
        elif i = nops(w) then
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kb    ,kb0))
        end if
      end do;
      return [`*`(entries(w1,'nolist')), `*`(entries(pp,'nolist'))]
    end if;
    if mode = `*` then
      if w :: (anything^freeof(var)) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(`^`, [], [op(2,w)])], `*`, kb1, kb0)
      elif w :: exp(anything) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(exp, [], [])], `+`, kb1, kb0)
      elif w :: (freeof(var)^anything) then
        return unproduct(op(2,w), var, loop,
                         [op(heap), Stmt(`^`, [op(1,w)], [])], `+`, kb1, kb0)
      end if
    end if;
    if mode = `+` and w :: `*` then
      s, r := selectremove(depends, w, var);
      if s :: `*` then
        # Nonlinear %1 (time to reread kiselyov-lifted?)
      else
        return unproduct(s, var, loop,
                         [op(heap), Stmt(`*`, [], [r])], `+`, kb1, kb0)
      end if
    end if;
    if w :: And(specfunc(`if`(mode = `*`, {product, Product}, {sum, Sum})),
                anyfunc(anything, name=range(freeof(var)))) then
      x, kb := genType(op([2,1],w),
                       HInt(Bound(`>=`,op([2,2,1],w)),
                            Bound(`<=`,op([2,2,2],w))),
                       kb1,
                       w, var, loop, heap);
      return unproduct(eval(op(1,w), op([2,1],w)=x), var, loop,
                       [op(heap), Binder(op(0,w), kb1)], mode, kb, kb0)
    end if;
    if mode = `*` and w :: '{`+`, specfunc({sum, Sum})}' then
      # Maybe this w is one of those big sums involving products that are
      # always equal to 1, left behind by the density of Categorical
      w1 := graft(split(peel(lift_piecewise(w))));
      w1 := combine(rebase_upper(w1));
      w1 := combine(rebase_lower(w1));
      return [wrap(heap, w1, mode, kb1, kb0), 1]
    end if;
    return [wrap(heap, w, mode, kb1, kb0), 1]
  end proc;

  enter_piecewise := proc(ee, kb0::t_kb, mode::identical(`*`,`+`), $)
    local e, kb, mo;
    e  := ee;
    kb := kb0;
    mo := mode();
    while e :: 'specfunc(piecewise)' and nops(e) = 3 do
      if op(3,e) = mo then
        kb := assert(op(1,e), kb);
        e := op(2,e);
      elif op(2,e) = mo then
        kb := assert(Not(op(1,e)), kb);
        e := op(3,e);
      else
        break;
      end if;
    end do;
    e, kb
  end proc;

  wrap := proc(heap::list, e1, mode1::identical(`*`,`+`),
               kb1::t_kb, kb0::t_kb, $)
    local e, kb, mode, i, entry, rest, var, new_rng, make,
       dom_spec, w, arrrgs;
    e    := e1;
    kb   := kb1;
    mode := mode1;
    for i from nops(heap) to 1 by -1 do
      entry := op(i,heap);
      if entry :: t_binder then
        if not (op(1,entry) in `if`(mode=`+`, {sum,Sum},
                                              {product,Product})) then
          print("Warning: heap mode inconsistency", heap, mode1)
        end if;
        e := simplify_assuming(e, op(2,entry));
        e, kb := enter_piecewise(e, kb, mode);
        rest := kb_subtract(kb, op(2,entry));
        new_rng, rest := selectremove(type, rest,
          {[identical(genType), name, specfunc(HInt)],
           [identical(genLet), name, anything]});
        if not (new_rng :: [list]) then
          error "kb_subtract should return exactly one gen*"
        end if;
        new_rng := op(new_rng);
        var     := op(2,new_rng);
        if op(1,new_rng) = genType then
          make    := op(1,entry);
          new_rng := range_of_HInt(op(3,new_rng));
        else # op(1,new_rng) = genLet
          make    := eval;
          new_rng := op(3,new_rng);
        end if;
        dom_spec, rest := selectremove(depends,
          map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest),
          var);
        (e, w) := selectremove(depends, convert(e, 'list', `*`), var);
        w := `*`(op(w));
        if mode = `*` and not (w = 1) then
          w := w ^ `if`(make=eval,eval,sum)
                       (piecewise_And(dom_spec, 1, 0), var=new_rng);
        end if;
        e := w * make(piecewise_And(dom_spec, `*`(op(e)), mode()), var=new_rng);
        kb := foldr(assert, op(2,entry), op(rest));
      elif entry :: t_stmt then
        # We evaluate arrrgs first, in case op(1,stmt) is an operation (such as
        # piecewise) that looks ahead at how many arguments it is passed before
        # they are evaluated.
        arrrgs := op(op(2,entry)), e, op(op(3,entry));
        e      := op(1,entry)(arrrgs);
        if entry :: t_exp then
          if mode <> `+` then
            print("Warning: heap mode inconsistency?", heap, mode1)
          end if;
          mode := `*`;
        end if
      else error "Malformed heap entry %1", entry end if
    end do;
    if mode <> `*` then
      print("Warning: heap mode inconsistency??", heap, mode1)
    end if;
    e, kb := enter_piecewise(e, kb, mode);
    rest := kb_subtract(kb, kb0);
    rest := map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest);
    piecewise_And(rest,e,mode())
  end proc;

  # Rewrite product(piecewise(i+42=lo+42,th,el),i=lo..hi)
  # to eval(th,i=lo)*product(el,i=lo+1..hi)
  peel := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(specfunc(piecewise), name=range))',
    proc(e, $)
      local body, x, r, line, test, make, here, rest, res;
      body := op(1,e);
      if not (1<nops(body) and op(1,body)::{`=`,`<`,`<=`}) then return e end if;
      x, r := op(op(2,e));
      line := op([1,1],body) - op([1,2],body);
      if 1 = degree(line, x) then
        if op(1,body) :: `=`  then
          test := proc (y,z,$)
            if Testzero(eval(line, x=y)) then true
            else FAIL end if
          end proc;
        elif op(1,body) :: `<` then
          test := proc (y,z,$)
            local l;
            l := [eval(line, x=y), eval(line, x=z)];
            if   l :: [negative, nonnegative] then true
            elif l :: [nonnegative, negative] then false
            else FAIL end if
          end proc;
        elif op(1,body) :: `<=` then
          test := proc (y,z,$)
            local l;
            l := [eval(line, x=y), eval(line, x=z)];
            if   l :: [nonpositive, positive] then true
            elif l :: [positive, nonpositive] then false
            else FAIL end if
          end proc;
        end if;
        if op(0,e) in {sum,Sum} then
          make := `+`;
        elif op(0,e) in {product,Product} then
          make := `*`;
        end if;
        here := op(2,body);
        if nops(body)=2 then
          rest := 0;
        elif nops(body)=3 then
          rest := op(3,body);
        elif {op([1,0],body) , op([3,0],body)} = {`<`, `<=`}
          and op([1,1],body) = op([3,2],body)
          and op([1,2],body) = op([3,1],body) then
          rest := op(4,body);
        else
          rest := subsop(1=NULL,2=NULL,body);
        end if;
        res := test(lhs(r), lhs(r)+1);
        if res <> FAIL then
          return make(eval(`if`(res, here, rest), x=lhs(r)),
                      subsop(1 = `if`(res, rest, here), [2,2,1]=lhs(r)+1, e));
        end if;
        res := test(rhs(r), rhs(r)-1);
        if res <> FAIL then
          return make(eval(`if`(res, here, rest), x=rhs(r)),
                      subsop(1 = `if`(res, rest, here), [2,2,2]=rhs(r)-1, e));
        end if;
      end if;
      e
    end proc);
  end proc:

  # Expand sum(a*(b-c),q) to sum(a*b,q)-sum(a*c,q)
  split := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum}),
                        anyfunc(And(`*`,Not(`*`(Not(`+`)))),name=anything))',
    proc(e, $)
      local terms, x;
      terms := convert(expand(op(1,e), op(indets(op(1,e), function))),
                       'list', `+`);
      x := op([2,1],e);
      `+`(op(map(proc(term, $)
        local s, r;
        s, r := selectremove(depends, convert(term, 'list', `*`), x);
        `*`(op(r), subsop(1=`*`(op(s)),e))
      end proc, terms)))
    end proc)
  end proc:

  # Simplify f(lo-1)*product(f(i),i=lo..hi) to product(f(i),i=lo-1..hi)
  graft := proc(ee, $)
    subsindets(ee, 'Or(And(`*`,Not(`*`(Not(specfunc({product,Product}))))),
                       And(`+`,Not(`+`(Not(specfunc({sum    ,Sum    }))))))',
    proc(e, $)
      local produce, factors, i, j;
      produce := `if`(e::`*`, '{product,Product}',
                              '{sum    ,Sum    }');
      factors := sort(convert(e,'list'),
                      key = (factor -> -numboccur(factor,produce)));
      for i from nops(factors) to 2 by -1 do
        for j from i-1 to 1 by -1 do
          if op(j,factors) :: 'And'('specfunc'(produce),
                                    'anyfunc(anything,name=range)') then
            if Testzero(op(i,factors) - eval(op([j,1],factors),
                 op([j,2,1],factors)=op([j,2,2,1],factors)-1)) then
              factors := subsop(i=NULL,applyop(`-`,[j,2,2,1],factors,1))
            elif Testzero(op(i,factors) - eval(op([j,1],factors),
                   op([j,2,1],factors)=op([j,2,2,2],factors)+1)) then
              factors := subsop(i=NULL,applyop(`+`,[j,2,2,2],factors,1))
            end if
          end if
        end do
      end do;
      op(0,e)(op(factors))
    end proc)
  end proc:

  # Normalize sum(f(i),i=2..hi) to sum(f(i+2),i=0..hi-2)
  rebase_lower := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,
                          name=Not({0,SymbolicInfinity,undefined})..anything))',
    proc(e, $)
      subsop([2,2,1]=0,
             applyop(`-`,
                     [2,2,2],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,1],e)),
                     op([2,2,1],e)))
    end proc)
  end proc:

  # Normalize sum(f(i),i=lo..2) to sum(f(i+2),i=lo-2..0)
  rebase_upper := proc(ee, $)
    subsindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,
                          name=anything..Not({0,SymbolicInfinity,undefined})))',
    proc(e, $)
      subsop([2,2,2]=0,
             applyop(`-`,
                     [2,2,1],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,2],e)),
                     op([2,2,2],e)))
    end proc)
  end proc:

  ModuleLoad := proc($)
    # Override csgn to work a little bit harder on piecewise and sum
    # (to get rid of csgn(1/2+1/2*sum(piecewise(...,1,0),...))
    #  produced by int on a Gaussian mixture model)
    unprotect(csgn);
    csgn := overload([
      # Handle if the csgn of a piecewise doesn't depend on which branch
      proc(a :: specfunc(piecewise), $)
        option overload;
        local r, i;
        r := {seq(`if`(i::even or i=nops(a), csgn(op(i,a)), NULL),
                  i=1..nops(a))};
        if nops(r)=1 then return op(r) end if;
        if not assigned(_Envsignum0) then
          r := r minus {0};
          if nops(r)=1 then return op(r) end if;
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      # Handle if the csgn of a sum doesn't depend on the bound variable
      proc(a :: And(specfunc({sum, Sum}), anyfunc(anything, name=range)), $)
        option overload;
        local r;
        r := csgn(op(1,a));
        if not depends(r,op([2,1],a)) then
          return signum(op([2,2,2],a)+1-op([2,2,1],a)) * r
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      csgn]);
    protect(csgn);
  end proc;

  ModuleLoad();

end module; # Loop