Refute.refute_goal: canonical goal addresses from 1 (renamed from refute_subgoal to clarify change in semantics);
command 'refute': Proof.flat_goal provides standard view on internally structured Isar goal, suitable for (semi)automated tools;
Arith = FOL +
classes arith < term
consts "0" :: "'a::arith" ("0")
"1" :: "'a::arith" ("1")
"+" :: "['a::arith,'a] => 'a" (infixl 60)
end