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Description: Define the "proves" relation on a set. A wff is true in a model M if for every valuation s e. ( M ^m _om ) , the interpretation of the wff using the membership relation on M is true. Since |= is defined in terms of the interpretations making the given formula true, it is not defined on the empty "model" M = (/) , since there are no interpretations. In particular, the empty set on the LHS of |= should not be interpreted as the empty model. Statement prv0 shows that our definition yields (/) |= U for all formulas, though of course the formula E. x x = x is not satisfied on the empty model. (Contributed by Mario Carneiro, 14-Jul-2013)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-prv |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cprv | ||
| 1 | vm | ||
| 2 | vu | ||
| 3 | 1 | cv | |
| 4 | csate | ||
| 5 | 2 | cv | |
| 6 | 3 5 4 | co | |
| 7 | cmap | ||
| 8 | com | ||
| 9 | 3 8 7 | co | |
| 10 | 6 9 | wceq | |
| 11 | 10 1 2 | copab | |
| 12 | 0 11 | wceq |