proved base case for drf guarantee
finish the diamond theorem!!! but many lemmas are not proved yet
restructure the layout of proofs
finish the proofs of a/b step_event_read_or_none
finish the read_context_invariance theorems
finish proof of write_context_invariance
finish proofs for lock_context_invariance(s)
finish the proofs of unlock_context_invariance(s)
remove trivial rules for lock/unlock and add to "stuck" rules; finish all theorems related to diamond theorem
remove useless files