Metamath Proof Explorer


Theorem hvsubsub4

Description: Hilbert vector space addition/subtraction law. (Contributed by NM, 2-Apr-2000) (New usage is discouraged.)

Ref Expression
Assertion hvsubsub4 ABCDA-B-C-D=A-C-B-D

Proof

Step Hyp Ref Expression
1 oveq1 A=ifAA0A-B=ifAA0-B
2 1 oveq1d A=ifAA0A-B-C-D=ifAA0-B-C-D
3 oveq1 A=ifAA0A-C=ifAA0-C
4 3 oveq1d A=ifAA0A-C-B-D=ifAA0-C-B-D
5 2 4 eqeq12d A=ifAA0A-B-C-D=A-C-B-DifAA0-B-C-D=ifAA0-C-B-D
6 oveq2 B=ifBB0ifAA0-B=ifAA0-ifBB0
7 6 oveq1d B=ifBB0ifAA0-B-C-D=ifAA0-ifBB0-C-D
8 oveq1 B=ifBB0B-D=ifBB0-D
9 8 oveq2d B=ifBB0ifAA0-C-B-D=ifAA0-C-ifBB0-D
10 7 9 eqeq12d B=ifBB0ifAA0-B-C-D=ifAA0-C-B-DifAA0-ifBB0-C-D=ifAA0-C-ifBB0-D
11 oveq1 C=ifCC0C-D=ifCC0-D
12 11 oveq2d C=ifCC0ifAA0-ifBB0-C-D=ifAA0-ifBB0-ifCC0-D
13 oveq2 C=ifCC0ifAA0-C=ifAA0-ifCC0
14 13 oveq1d C=ifCC0ifAA0-C-ifBB0-D=ifAA0-ifCC0-ifBB0-D
15 12 14 eqeq12d C=ifCC0ifAA0-ifBB0-C-D=ifAA0-C-ifBB0-DifAA0-ifBB0-ifCC0-D=ifAA0-ifCC0-ifBB0-D
16 oveq2 D=ifDD0ifCC0-D=ifCC0-ifDD0
17 16 oveq2d D=ifDD0ifAA0-ifBB0-ifCC0-D=ifAA0-ifBB0-ifCC0-ifDD0
18 oveq2 D=ifDD0ifBB0-D=ifBB0-ifDD0
19 18 oveq2d D=ifDD0ifAA0-ifCC0-ifBB0-D=ifAA0-ifCC0-ifBB0-ifDD0
20 17 19 eqeq12d D=ifDD0ifAA0-ifBB0-ifCC0-D=ifAA0-ifCC0-ifBB0-DifAA0-ifBB0-ifCC0-ifDD0=ifAA0-ifCC0-ifBB0-ifDD0
21 ifhvhv0 ifAA0
22 ifhvhv0 ifBB0
23 ifhvhv0 ifCC0
24 ifhvhv0 ifDD0
25 21 22 23 24 hvsubsub4i ifAA0-ifBB0-ifCC0-ifDD0=ifAA0-ifCC0-ifBB0-ifDD0
26 5 10 15 20 25 dedth4h ABCDA-B-C-D=A-C-B-D