rebuilt from fresh copy of Bitstream Vera, for improved quality of regular text glyphs;
misc cleanup of mathematical glyphs, with bold version synthesized by fontforge;
(benchmark Isabelle
:assumption (not (exists (?x1 Int) (forall (?x2 Int) (?x3 Int) (implies (and (< 0 ?x2) (< 0 ?x3)) (< 0 (+ ?x2 ?x3))))))
:formula true
)