Metamath Proof Explorer


Definition df-mid

Description: Define the midpoint operation. Definition 10.1 of Schwabhauser p. 88. See ismidb , midbtwn , and midcgr . (Contributed by Thierry Arnoux, 9-Jun-2019)

Ref Expression
Assertion df-mid mid𝒢=gVaBaseg,bBasegιmBaseg|b=pInv𝒢gma

Detailed syntax breakdown

Step Hyp Ref Expression
0 cmid classmid𝒢
1 vg setvarg
2 cvv classV
3 va setvara
4 cbs classBase
5 1 cv setvarg
6 5 4 cfv classBaseg
7 vb setvarb
8 vm setvarm
9 7 cv setvarb
10 cmir classpInv𝒢
11 5 10 cfv classpInv𝒢g
12 8 cv setvarm
13 12 11 cfv classpInv𝒢gm
14 3 cv setvara
15 14 13 cfv classpInv𝒢gma
16 9 15 wceq wffb=pInv𝒢gma
17 16 8 6 crio classιmBaseg|b=pInv𝒢gma
18 3 7 6 6 17 cmpo classaBaseg,bBasegιmBaseg|b=pInv𝒢gma
19 1 2 18 cmpt classgVaBaseg,bBasegιmBaseg|b=pInv𝒢gma
20 0 19 wceq wffmid𝒢=gVaBaseg,bBasegιmBaseg|b=pInv𝒢gma