recover static nnf_ss from 6c0de045d127 -- avoid odd runtime warnings due to duplication of not_not;
recover static nnf_ss from 6c0de045d127 -- avoid odd runtime warnings due to duplication of not_not;

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