Malformed token: error msg;
scan: explicit handling of malformed symbols from previous stage;
source: interactive flag indicates intermittent error_msg;
tuned;
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