optimize relevance filter by doing a Table.fold directly rather than destroying the datastructure each time;
saves 2 sec per Sledgehammer invocation on my laptop!
(* Title: Sequents/ROOT.ML
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1991 University of Cambridge
Classical Sequent Calculus based on Pure Isabelle.
*)
use_thys ["LK", "ILL", "ILL_predlog", "Washing", "Modal0", "T", "S4", "S43"];