added delcongs, Delcongs, unsafe_solver, safe_solver, FOL_basic_ss,
safe_asm_more_full_simp_tac
new addss (old version retained as unsafe_addss),
new auto_tac (old version retained as unsafe_auto_tac),
clasimpset with modification functions
Gate2 = FOL +
consts "~&" :: "[o,o] => o" (infixl 35)
"#" :: "[o,o] => o" (infixl 30)
If :: "[o,o,o] => o" ("if _ then _ else _")
rules nand_def "P ~& Q == ~(P & Q)"
xor_def "P # Q == P & ~Q | ~P & Q"
If_def "if P then Q else R == P&Q | ~P&R"
end