Description: Degenerated case 1 for vertices: The set of vertices of the empty set is the empty set. (Contributed by AV, 24-Sep-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | vtxval0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0nelxp | ||
2 | 1 | iffalsei | |
3 | vtxval | ||
4 | base0 | ||
5 | 2 3 4 | 3eqtr4i |