prove stronger statements about undesirable histories
prove stronger statements about undesirable histories

instead of aborting attempted proofs of undesirable example histories,
prove that these undesirable example histories can never be legal.

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl