Description: Define the Godel-set of equivalence. Here the arguments U and V are also Godel-sets corresponding to smaller formulas. Note that this is aclass expression, not a wff. (Contributed by Mario Carneiro, 14-Jul-2013)
Ref | Expression | ||
---|---|---|---|
Assertion | df-gobi | |- <->g = ( u e. _V , v e. _V |-> ( ( u ->g v ) /\g ( v ->g u ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
0 | cgob | |- <->g |
|
1 | vu | |- u |
|
2 | cvv | |- _V |
|
3 | vv | |- v |
|
4 | 1 | cv | |- u |
5 | cgoi | |- ->g |
|
6 | 3 | cv | |- v |
7 | 4 6 5 | co | |- ( u ->g v ) |
8 | cgoa | |- /\g |
|
9 | 6 4 5 | co | |- ( v ->g u ) |
10 | 7 9 8 | co | |- ( ( u ->g v ) /\g ( v ->g u ) ) |
11 | 1 3 2 2 10 | cmpo | |- ( u e. _V , v e. _V |-> ( ( u ->g v ) /\g ( v ->g u ) ) ) |
12 | 0 11 | wceq | |- <->g = ( u e. _V , v e. _V |-> ( ( u ->g v ) /\g ( v ->g u ) ) ) |