Metamath Proof Explorer


Theorem edg0iedg0

Description: There is no edge in a graph iff its edge function is empty. (Contributed by AV, 15-Dec-2020) (Revised by AV, 8-Dec-2021)

Ref Expression
Hypotheses edg0iedg0.i I = iEdg G
edg0iedg0.e E = Edg G
Assertion edg0iedg0 Fun I E = I =

Proof

Step Hyp Ref Expression
1 edg0iedg0.i I = iEdg G
2 edg0iedg0.e E = Edg G
3 edgval Edg G = ran iEdg G
4 2 3 eqtri E = ran iEdg G
5 4 eqeq1i E = ran iEdg G =
6 5 a1i Fun I E = ran iEdg G =
7 1 eqcomi iEdg G = I
8 7 rneqi ran iEdg G = ran I
9 8 eqeq1i ran iEdg G = ran I =
10 9 a1i Fun I ran iEdg G = ran I =
11 funrel Fun I Rel I
12 relrn0 Rel I I = ran I =
13 12 bicomd Rel I ran I = I =
14 11 13 syl Fun I ran I = I =
15 6 10 14 3bitrd Fun I E = I =