Metamath Proof Explorer


Theorem hvaddsubass

Description: Associativity of sum and difference of Hilbert space vectors. (Contributed by NM, 27-Aug-2004) (New usage is discouraged.)

Ref Expression
Assertion hvaddsubass ABCA+B-C=A+B-C

Proof

Step Hyp Ref Expression
1 neg1cn 1
2 hvmulcl 1C-1C
3 1 2 mpan C-1C
4 ax-hvass AB-1CA+B+-1C=A+B+-1C
5 3 4 syl3an3 ABCA+B+-1C=A+B+-1C
6 hvaddcl ABA+B
7 hvsubval A+BCA+B-C=A+B+-1C
8 6 7 stoic3 ABCA+B-C=A+B+-1C
9 hvsubval BCB-C=B+-1C
10 9 3adant1 ABCB-C=B+-1C
11 10 oveq2d ABCA+B-C=A+B+-1C
12 5 8 11 3eqtr4d ABCA+B-C=A+B-C