The FRAT format and FRAT-rs

FRAT-rs is a toolchain for processing and transforming files in the FRAT format.

Usage

FRAT-rs can be compiled using make. (It is written in Rust, so you will need to get Rust first to put cargo in your path.)

• frat-rs elab FRATFILE [--full] [-s|-ss] [-m[NUM]] [DIMACSFILE [LRATFILE] [-v] [-c]]: Elaborates FRATFILE, the unsatisfiability proof of DIMACSFILE, and produces the corresponding LRATFILE.

  • If --full is specified, the entire FRAT file is checked, including steps that do not contribute to the final contradiction. (The default is to skip these steps, so we might generate a valid proof without ever noticing that the step that was skipped is not well formed.)

  • If -s is specified, the FRAT file is checked in "strict mode", which means that bogus proofs in l steps will be rejected. (The default behavior is to instead fall back on no-hint mode if the hint is wrong.)

  • If -ss is specified, the FRAT file is checked in "extra-strict mode", in which l steps cannot be omitted.

  • If -m is specified, the intermediate file (between FRAT and LRAT) will be generated in memory instead of on disk, which might be faster. The optional NUM argument is a size hint for the initial allocation in bytes, which defaults to 5 times the size of the FRATFILE.

  • If DIMACSFILE is specified, the resulting output will be checked against the given CNF, otherwise only the first phase of elaboration will run, producing a FRATFILE.temp file but no other output. (This temporary file is useful as input to refrat.)

  • If LRATFILE is specified, the output will be placed in LRATFILE, otherwise the elaborator will run but no output will be produced.

  • If -v is specified, the LRAT file is passed directly to lratchk. Omitting LRATFILE and specifying -v is a way to verify FRAT files without otherwise generating output.

  • If -c is specified (requires LRATFILE), comment lines from the original FRAT file will be transmitted to the LRATFILE. This is a good way to align important points in the proof with the output, but it is disabled by default since some LRAT checkers don't support comments.

  This is the main subcommand you want to use, if you are a solver developer producing FRAT files.

• frat-rs lratchk DIMACSFILE LRATFILE: Checks LRATFILE against the input problem DIMACSFILE.

  This is essentially the same as lrat-check.c but it is more robust (at the time of writing) and has no known bugs. It is provided as a convenience for FRAT and LRAT file testing, but for actual high assurance scenarios you should use elab to generate an LRAT file and then use a formally verified LRAT checker like cake_lpr to check the resulting file.

• frat-rs stat FRATFILE: Analyzes FRATFILE and displays statistics

• frat-rs strip-frat FRATFILE NEWFRATFILE: Processes FRATFILE, and produces a corresponding NEWFRATFILE with 0% annotations

• frat-rs refrat ELABFILE FRATFILE: Processes ELABFILE, a temporary file produced by the first elaboration pass of frat-rs, and produces FRATFILE, a corresponding FRAT proof with 100% annotations

• frat-rs to-cnf FRATFILE > DIMACSFILE: FRAT files contain a copy of the CNF inside them. This command constructs a CNF file that FRATFILE could be a proof of, and writes it to stdout (or pipes it to DIMACSFILE in this example)

• frat-rs from-drat DIMACSFILE DRATFILE FRATFILE: Processes DIMACSFILE and DRATFILE to produce a corresponding FRATFILE with 0% annotations. Note that despite the name, this also works on PR files, and will translate them into FRAT files with PR steps.

• frat-rs from-pr DIMACSFILE PRFILE FRATFILE: Processes DIMACSFILE and PRFILE to produce a corresponding FRATFILE with no PR steps. This implements the pr2drat algorithm, but with proofs supplied in the resulting FRAT file.

  Note that elab can directly handle PR steps in FRAT files, and they will be preserved in the output (resulting in LPR files instead of LRAT). So the main reason you would use this command is if you want pure LRAT output, or just as another way to slice data to get another data set.

• Experimental subcommands:

  • frat-rs drat-trim: A clone of drat-trim in true "Rewrite it in Rust" fashion. It has exactly the same behavior and options as the original, see the README there for more info.

  • frat-rs dratchk DIMACSFILE DRATFILE: Checks DRATFILE against the input problem DIMACSFILE (unmaintained)