anchor.diff:         ("~ false = true"    :swe "~ false = true"    :value '(:|Bool| . T))
          ("~ (~ true) = true"   :swe "~ (~ true) = true"   :value '(:|Bool| . T))
          ("~ (~ false) = false" :swe "~ (~ false) = false" :value '(:|Bool| . T))
  -       ("[(~)] = [(~)]"     :swe "[(~)] = [(~)]"     :value '(:|Bool| . T))
  +       ("[(~)(true)] = [(~)(true)]"     :swe "[(~)(true)] = [(~)(true)]"     :value '(:|Bool| . T))
          ;; Boolean [  2]:  op &   infixr 15 : Boolean * Boolean -> Boolean 
          ("(&& ( false , false )) = false" :swe "(&& ( false , false )) = false" :value '(:|Bool| . T))
          ("let A = id ( false , false ) in (&& A) = false" :swe "let A = id ( false , false ) in (&& A) = false" :value '(:|Bool| . T))
  
positive.code:        ("let A = id ( true , false ) in (=> A) = false" :swe "let A = id ( true , false ) in (=> A) = false" :value '(:|Bool| . T))
         ("(=> ( true , true )) = true" :swe "(=> ( true , true )) = true" :value '(:|Bool| . T))
         ("let A = id ( true , true ) in (=> A) = true" :swe "let A = id ( true , true ) in (=> A) = true" :value '(:|Bool| . T))
         ;; Boolean [  5]:  op <=> infixr 12 : Boolean * Boolean -> Boolean 
         ("(<=> ( false , false )) = true" :swe "(<=> ( false , false )) = true" :value '(:|Bool| . T))
         ("let A = id ( false , false ) in (<=> A) = true" :swe "let A = id ( false , false ) in (<=> A) = true" :value '(:|Bool| . T))
  
negative.code:        ("let A = id ( true , false ) in (&& A) = false" :swe "let A = id ( true , false ) in (&& A) = false" :value '(:|Bool| . T))
         ("(&& ( true , true )) = true" :swe "(&& ( true , true )) = true" :value '(:|Bool| . T))
         ("let A = id ( true , true ) in (&& A) = true" :swe "let A = id ( true , true ) in (&& A) = true" :value '(:|Bool| . T))
         ("[(&&)(true,true)] = [(&&)(true,true)]"     :swe "[(&&)(true,true)] = [(&&)(true,true)]"     :value '(:|Bool| . T))
         ;; Boolean [  3]:  op ||  infixr 14 : Boolean * Boolean -> Boolean 
         ("(|| ( false , false )) = false" :swe "(|| ( false , false )) = false" :value '(:|Bool| . T))
         ("let A = id ( false , false ) in (|| A) = false" :swe "let A = id ( false , false ) in (|| A) = false" :value '(:|Bool| . T))
  