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/*++
Copyright (c) 2011 Microsoft Corporation
Module Name:
tseitin_cnf_tactic.h
Abstract:
Author:
Leonardo (leonardo) 2011-12-29
Tactic Documentation:
## Tactic tseitin-cnf
### Short Description
Convert goal into CNF using tseitin-like encoding (note: quantifiers are ignored).
### Long Description
Puts an assertion set in CNF.
Auxiliary variables are used to avoid blowup.
Features:
- Efficient encoding is used for commonly used patterns such as:
`(iff a (iff b c))`
`(or (not (or a b)) (not (or a c)) (not (or b c)))`
- Efficient encoding is used for chains of if-then-elses
- Distributivity is applied to non-shared nodes if the blowup is acceptable.
- The features above can be disabled/enabled using parameters.
- The assertion-set is only modified if the resultant set of clauses is "acceptable".
Notes:
- Term-if-then-else expressions are not handled by this strategy.
This kind of expression should be processed by other strategies.
- Quantifiers are treated as "theory" atoms. They are viewed
as propositional variables by this strategy.
- The assertion set may contain free variables.
- This strategy assumes the assertion_set_rewriter was used before invoking it.
In particular, it is more effective when "and" operators
were eliminated.
### Example
```z3
(declare-const a Bool)
(declare-const b Bool)
(declare-const c Bool)
(assert (= a (= b c)))
(apply tseitin-cnf)
```
--*/
class ast_manager;
class tactic;
tactic * ;
tactic * ;
/*
ADD_TACTIC("tseitin-cnf", "convert goal into CNF using tseitin-like encoding (note: quantifiers are ignored).", "mk_tseitin_cnf_tactic(m, p)")
ADD_TACTIC("tseitin-cnf-core", "convert goal into CNF using tseitin-like encoding (note: quantifiers are ignored). This tactic does not apply required simplifications to the input goal like the tseitin-cnf tactic.", "mk_tseitin_cnf_core_tactic(m, p)")
*/