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Description: Define the Godel-set of existential quantification. Here N e.om corresponds to vN , and U represents another formula, and this expression is [ E. x ph ] = E.g N U where x is the N -th variable, U = [ ph ] is the code for ph . Note that this is a class expression, not a wff. (Contributed by Mario Carneiro, 14-Jul-2013)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-goex | |- E.g N U = -.g A.g N -.g U |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cN | |- N |
|
| 1 | cU | |- U |
|
| 2 | 1 0 | cgox | |- E.g N U |
| 3 | 1 | cgon | |- -.g U |
| 4 | 3 0 | cgol | |- A.g N -.g U |
| 5 | 4 | cgon | |- -.g A.g N -.g U |
| 6 | 2 5 | wceq | |- E.g N U = -.g A.g N -.g U |