KwickClips Computer Systems · 42 sec · free
Is every valid formula satisfiable?
Short answer. Yes.
Is p → q valid?
No, it is satisfiable but not valid.
Three words
| Word | True in | Same as |
|---|---|---|
| Valid | every row | tautology |
| Satisfiable | some row | not always F |
| Unsatisfiable | no row | contradiction |
Remember
| Valid is always satisfiable |
| p → q: satisfiable, not valid |
Is every satisfiable formula valid? No. Here is the difference. Valid is true in every row. Satisfiable needs just one true row. Unsatisfiable has none. Two points. Valid is satisfiable. Satisfiable may not be valid.
This clip is from the full lesson: Propositional Logic: Propositions, Connectives and Valid Formulae — 8 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: ISC Class 11 Computer Science (868), ISC Class 12 Computer Science (868), ISC Class 12 Computer Science (868)
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