`module Cnf: ``LogtkCnf`

type`form =`

`LogtkFormula.FO.t`

type`symbol =`

`LogtkSymbol.t`

See "computing small normal forms", in the handbook of automated reasoning. All transformations are made on curried terms and formulas.

`val is_cnf : ``form -> bool`

Is the formula in CNF?

`val is_lit : ``form -> bool`

Literal?

`val is_clause : ``form list -> bool`

Is it a clause, ie a list of literals?

`val miniscope : ``?distribute_exists:bool -> form -> form`

Apply miniscoping transformation to the term.

`distribute_exists`

: see whether ?X:(p(X)|q(X)) should be
transformed into (?X: p(X) | ?X: q(X)). Default: `false`

type`clause =`

`form list`

Basic clause representation, as list of literals

`type `

options =

`|` |
`DistributeExists` |
|||

`|` |
`DisableRenaming` |
|||

`|` |
`InitialProcessing of ` |
`(*` |
any processing, at the beginning
| `*)` |

`|` |
`PostNNF of ` |
`(*` |
any processing that keeps negation at leaves
| `*)` |

`|` |
`PostSkolem of ` |
`(*` |
must not introduce variables nor negations
| `*)` |

Options are used to tune the behavior of the CNF conversion.

- DistributeExists if enabled, will distribute existential quantifiers over disjunctions. This can make skolem symbols smaller (smaller arity) but introduce more of them.
- DisableRenaming disables formula renaming. Can re-introduce the worst-case exponential behavior of CNF.
- InitialProcessing a simplification function that is called before CNF starts.
- PostNNF transformation applied just after reduction to NNF. Its output must not break the NNF form (negation at root only).
- PostSkolem transformation applied just after skolemization. It must not break skolemization nor NNF (no quantifier, no non-leaf negation).
- DefLimit number of expected clauses above which a sub-formula is
renamed (unless
`DisableRenaming`

is present).

`val cnf_of : ``?opts:options list ->`

?ctx:LogtkSkolem.ctx -> form -> clause list

LogtkTransform the clause into proper CNF; returns a list of clauses.
Options are used to tune the behavior.

`val cnf_of_list : ``?opts:options list ->`

?ctx:LogtkSkolem.ctx -> form list -> clause list