One, life 题公 type of attribute
| Wing true formula (tautology) |
Any truth assignment are true |
| Can satisfy the formula |
There is a set of truth assignment is true |
| Yong fake formula (contradiction) |
Any truth assignment are false |
Measure to judge:
1 truth table method
2 into the primary extraction expression (Σmi) / main conjunctive expression (πMi)
3 propositional logic symbolic expressions and simplification
Second, the effective conclusion
1, the effective conclusion of the definition
Premise -> Conclusion
The premise is true or false conclusion, is the establishment of both a valid conclusion
2, the determination is not a valid conclusion
- familiar with eight valid inference rules (PT CP F ES EG US UG)
ES inference rules to ensure that when the first use;
When using the UG rules, introduced by the object is not to promote ES
Third, the symbolic proposition
1) Unless there is time before I go to the movies
I go to the movies -> I have the time
2) I do not admit that you are right, unless the sun from the west
The sun does not rise in the west -> I do not admit that you are right
3）P当Q......P->Q
4) P only when Q ..... Q-> P
5) P if and only if Q ...... P <-> Q
- the time of propositional symbols, corresponding to the whole quantifier ->, the corresponding existential quantifier conjunctive
6) all A are B ...... (All X) (A (X) -> B (X))
7) A satisfies some B ...... (Exist X) (A (X) && B (X))
Four other knowledge (continually updated)
All entries minimum disjunctive - never really formula;
Conjunctive all great items - never fake ceremony.
Logical operators priority (high to low):
And the introduction of non or equivalent.