This is an inofficial mirror of http://metamath.tirix.org for personal testing of a visualizer extension only.
Description: The null graph represented by an empty set is a hypergraph. (Contributed by AV, 9-Oct-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | uhgr0 | |- (/) e. UHGraph |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | f0 | |- (/) : (/) --> (/) |
|
| 2 | dm0 | |- dom (/) = (/) |
|
| 3 | pw0 | |- ~P (/) = { (/) } |
|
| 4 | 3 | difeq1i | |- ( ~P (/) \ { (/) } ) = ( { (/) } \ { (/) } ) |
| 5 | difid | |- ( { (/) } \ { (/) } ) = (/) |
|
| 6 | 4 5 | eqtri | |- ( ~P (/) \ { (/) } ) = (/) |
| 7 | 2 6 | feq23i | |- ( (/) : dom (/) --> ( ~P (/) \ { (/) } ) <-> (/) : (/) --> (/) ) |
| 8 | 1 7 | mpbir | |- (/) : dom (/) --> ( ~P (/) \ { (/) } ) |
| 9 | 0ex | |- (/) e. _V |
|
| 10 | vtxval0 | |- ( Vtx ` (/) ) = (/) |
|
| 11 | 10 | eqcomi | |- (/) = ( Vtx ` (/) ) |
| 12 | iedgval0 | |- ( iEdg ` (/) ) = (/) |
|
| 13 | 12 | eqcomi | |- (/) = ( iEdg ` (/) ) |
| 14 | 11 13 | isuhgr | |- ( (/) e. _V -> ( (/) e. UHGraph <-> (/) : dom (/) --> ( ~P (/) \ { (/) } ) ) ) |
| 15 | 9 14 | ax-mp | |- ( (/) e. UHGraph <-> (/) : dom (/) --> ( ~P (/) \ { (/) } ) ) |
| 16 | 8 15 | mpbir | |- (/) e. UHGraph |