Cull provably-unsatisfiable constructors - #59
Open
mwhicks1 wants to merge 1 commit into
Open
Conversation
…ctors Adds constructorPremisesUnsat, which telescopes a constructor's premises and tries simp_all/omega/decide on a False goal under a heartbeat budget; compileInductiveSchedule skips constructors proved dead. Uses only the constructor's own premises (never the input state), so it culls only never-satisfiable constructors and is a sound, opt-in optimization over the existing runtime backtracking. Includes VaultCullProof (by-hand disproofs plus keep-these witnesses) and cull tests on the vault and guarded-dereference all-combinations relations. Results recorded in Docs/Results.md.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The idea explored in PR #58 is that for a "state machine" we can inline multiple steps in sequence into a single branch, and thereby have later calls' preconditions affect earlier calls' generators. This sort of inlining will yield a state-space blowup: For N commands, there are N^k commands of inlined k-steps. One way of reducing the blowup is to drop unsatisfiable compositions. If command C1 could never be followed by C2, there is no sense in discovering this at run-time and causing backtracking -- rule it out at compile time.
This PR adds functionality to drop unsatisfiable constructors in an inductive relation, assuming an inlining pass has preceded this one. This functionality must be enabled by a flag. Experiments and examples are included.
The inlining functionality will be in a future PR. Another useful PR would be to cull inlined pairs that add no value, i.e., that later conditions do not influence earlier generations, which perhaps the scheduler could identify.
By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.