LCF/fix/lfp_is_FIX: modified proof to suppress deep unification
LCF/fix/lfp_is_FIX: modified proof to suppress deep unification

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle