Metamath Proof Explorer


Theorem re1m1e0m0

Description: Equality of two left-additive identities. See resubidaddlid . Uses ax-i2m1 . (Contributed by SN, 25-Dec-2023)

Ref Expression
Assertion re1m1e0m0 1-1=0-0

Proof

Step Hyp Ref Expression
1 0red 0
2 1re 1
3 rersubcl 111-1
4 2 2 3 mp2an 1-1
5 4 a1i 1-1
6 ax-icn i
7 6 6 mulcli ii
8 ax-1cn 1
9 4 recni 1-1
10 7 8 9 addassi ii+1+1-1=ii+1+1-1
11 repncan3 111+1-1=1
12 2 2 11 mp2an 1+1-1=1
13 12 oveq2i ii+1+1-1=ii+1
14 10 13 eqtri ii+1+1-1=ii+1
15 ax-i2m1 ii+1=0
16 15 oveq1i ii+1+1-1=0+1-1
17 14 16 15 3eqtr3i 0+1-1=0
18 17 a1i 0+1-1=0
19 1 5 18 reladdrsub 1-1=0-0
20 19 mptru 1-1=0-0