Description: The vertex degree function on finite simple graphs is a function from vertices to nonnegative integers. (Contributed by AV, 12-Dec-2020)
Ref | Expression | ||
---|---|---|---|
Hypothesis | vtxdgfusgrf.v | |
|
Assertion | vtxdgfusgrf | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | vtxdgfusgrf.v | |
|
2 | fusgrfis | |
|
3 | fusgrusgr | |
|
4 | eqid | |
|
5 | eqid | |
|
6 | 4 5 | usgredgffibi | |
7 | 3 6 | syl | |
8 | usgrfun | |
|
9 | fundmfibi | |
|
10 | 3 8 9 | 3syl | |
11 | 7 10 | bitrd | |
12 | 2 11 | mpbid | |
13 | eqid | |
|
14 | 1 4 13 | vtxdgfisf | |
15 | 12 14 | mpdan | |