added exists_subtype; added internal/skolem (from Syntax/lexicon.ML); added generalize(T);
added exists_subtype;
added internal/skolem (from Syntax/lexicon.ML);
added generalize(T);

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