anchor.diff:  assert[name "foo"] bar.
   ----
   
  +[[graphical-proof]]
   === Graphical Display of Proofs
   
   A handy way of displaying the proof is to use http://graphviz.org/[graphviz]:
  
positive.code: - small tools (see directory `src/tools/`) to illustrate how to use the library
      and provide basic services (type-checking, reduction to CNF, etc.);
  
  == Documentation
  
  See http://c-cube.github.io/zipperposition/[this page].
  
negative.code: +
  there are several variations on literal rewrite rules:
  +
  - `rewrite forall x. p x` (short for `p x <=> true`)
  - `rewrite forall x. ~ p x` (short for `p x <=> false`)
  - `rewrite forall x. p x => q x`
    (one way rule, will rewrite `p x` but not `~ p x`; also called _polarized rewriting_)
  - `rewrite forall x. ~ p x => q x`
  