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Description: The null graph (as hypergraph) is a subgraph of all graphs. (Contributed by AV, 17-Nov-2020) (Proof shortened by AV, 28-Nov-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 0uhgrsubgr | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> S SubGraph G ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 3simpa | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ( G e. W /\ S e. UHGraph ) ) |
|
| 2 | 0ss | |- (/) C_ ( Vtx ` G ) |
|
| 3 | sseq1 | |- ( ( Vtx ` S ) = (/) -> ( ( Vtx ` S ) C_ ( Vtx ` G ) <-> (/) C_ ( Vtx ` G ) ) ) |
|
| 4 | 2 3 | mpbiri | |- ( ( Vtx ` S ) = (/) -> ( Vtx ` S ) C_ ( Vtx ` G ) ) |
| 5 | 4 | 3ad2ant3 | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ( Vtx ` S ) C_ ( Vtx ` G ) ) |
| 6 | eqid | |- ( iEdg ` S ) = ( iEdg ` S ) |
|
| 7 | 6 | uhgrfun | |- ( S e. UHGraph -> Fun ( iEdg ` S ) ) |
| 8 | 7 | 3ad2ant2 | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> Fun ( iEdg ` S ) ) |
| 9 | edgval | |- ( Edg ` S ) = ran ( iEdg ` S ) |
|
| 10 | uhgr0vb | |- ( ( S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ( S e. UHGraph <-> ( iEdg ` S ) = (/) ) ) |
|
| 11 | rneq | |- ( ( iEdg ` S ) = (/) -> ran ( iEdg ` S ) = ran (/) ) |
|
| 12 | rn0 | |- ran (/) = (/) |
|
| 13 | 11 12 | eqtrdi | |- ( ( iEdg ` S ) = (/) -> ran ( iEdg ` S ) = (/) ) |
| 14 | 10 13 | biimtrdi | |- ( ( S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ( S e. UHGraph -> ran ( iEdg ` S ) = (/) ) ) |
| 15 | 14 | ex | |- ( S e. UHGraph -> ( ( Vtx ` S ) = (/) -> ( S e. UHGraph -> ran ( iEdg ` S ) = (/) ) ) ) |
| 16 | 15 | pm2.43a | |- ( S e. UHGraph -> ( ( Vtx ` S ) = (/) -> ran ( iEdg ` S ) = (/) ) ) |
| 17 | 16 | a1i | |- ( G e. W -> ( S e. UHGraph -> ( ( Vtx ` S ) = (/) -> ran ( iEdg ` S ) = (/) ) ) ) |
| 18 | 17 | 3imp | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ran ( iEdg ` S ) = (/) ) |
| 19 | 9 18 | eqtrid | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> ( Edg ` S ) = (/) ) |
| 20 | egrsubgr | |- ( ( ( G e. W /\ S e. UHGraph ) /\ ( Vtx ` S ) C_ ( Vtx ` G ) /\ ( Fun ( iEdg ` S ) /\ ( Edg ` S ) = (/) ) ) -> S SubGraph G ) |
|
| 21 | 1 5 8 19 20 | syl112anc | |- ( ( G e. W /\ S e. UHGraph /\ ( Vtx ` S ) = (/) ) -> S SubGraph G ) |