cnf-utils

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This package implements a number of tools that operate on DIMACS CNF files.

Here is a short summary of the tools and their usage:

• cnf-cat [FILE] ...

  Concatenate the clauses of one or more CNF files.

• cnf-clause [[LITERAL] ... 0] ...

  Generate a CNF file containing the clauses specified on the command line. Example:

  $ cnf-clause 1 2 0 -1 3 0 p cnf 3 2 1 2 0 -1 3 0

• cnf-grep VARIABLE [FILE]

  Read the CNF file specified by FILE (or standard input if omitted) and output the clauses containing the variable VARIABLE. Example:

  $ cnf-clause 1 2 0 -1 3 0 | cnf-grep 2 p cnf 3 1 1 2 0

• cnf-pack [FILE]

  Read the CNF file specified by FILE (or standard input if omitted) and rename the variables so that they start at 1 and go to N, where N is the number of distinct variables in the input. Example:

  $ cnf-clause 100 101 0 | cnf-pack p cnf 2 1 1 2 0

• cnf-propagate [FILE]

  Read the CNF file specified by FILE (or standard input if omitted) and carry out unit propagation recursively until no further propagations can be made. Note that no clauses are removed; both unit clauses and tautologies (e.g. 1 -1 0) will remain in the output. Example:

  $ cnf-clause 1 2 0 -1 3 0 -3 0 | cnf-propagate p cnf 3 3 2 0 -1 0 -3 0

• cnf-shuffle-clauses [FILE]

  Shuffle the order of the clauses, but leave the order of literals within each clause intact.

• cnf-shuffle-literals [FILE]

  Shuffle the order of the literals within each clause, but leave the order of the clauses intact.

• cnf-shuffle-variables [FILE]

  rENAME the variables randomly using a one-to-one mapping. The resulting CNF output is equisatisfiable with the CNF input. Example:

  $ cnf-clause 1 2 3 0 | cnf-shuffle-variables p cnf 3 1 2 3 1 0

• cnf-sort-clauses [FILE]

  Order the clauses in ascending order. Example:

  $ cnf-clause 3 2 1 0 -3 -2 -1 0 | cnf-sort-clauses p cnf 3 2 -3 -2 -1 0 3 2 1 0

• cnf-sort-literals [FILE]

  Order the literals within each clause in ascending order. Example:

  $ cnf-clause 3 2 1 0 -3 -2 -1 0 | cnf-sort-literals p cnf 3 2 1 2 3 0 -3 -2 -1 0

• cnf-stat [FILE]

  Print some simple statistics about the CNF input. Example:

  $ cnf-stat 20-r-16-160-r-00-shuffle-1.cnf Literals: 121157 (61952 negative, 59205 positive) Clause length histogram: 1: 1 2: 15608 3: 29980