beta eta contract the Sledgehammer conjecture (and also the axioms, although this might not be needed), just like Metis does (implicitly);
another consequence of the transition to FOF
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