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 A B C A + B - C = A + B - C

Proof

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