added type homogenization, whereby all (isomorphic) infinite types are mapped to the same type (to reduce the number of different predicates/TFF-types)
Gate = FOL +
consts nand,xor :: "[o,o] => o"
rules nand_def "nand(P,Q) == ~(P & Q)"
xor_def "xor(P,Q) == P & ~Q | ~P & Q"
end