Metamath Proof Explorer


Theorem braval

Description: A bra-ket juxtaposition, expressed as <. A | B >. in Dirac notation, equals the inner product of the vectors. Based on definition of bra in Prugovecki p. 186. (Contributed by NM, 15-May-2006) (Revised by Mario Carneiro, 17-Nov-2013) (New usage is discouraged.)

Ref Expression
Assertion braval ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) → ( ( bra ‘ 𝐴 ) ‘ 𝐵 ) = ( 𝐵 ·ih 𝐴 ) )

Proof

Step Hyp Ref Expression
1 brafval ( 𝐴 ∈ ℋ → ( bra ‘ 𝐴 ) = ( 𝑥 ∈ ℋ ↦ ( 𝑥 ·ih 𝐴 ) ) )
2 1 fveq1d ( 𝐴 ∈ ℋ → ( ( bra ‘ 𝐴 ) ‘ 𝐵 ) = ( ( 𝑥 ∈ ℋ ↦ ( 𝑥 ·ih 𝐴 ) ) ‘ 𝐵 ) )
3 oveq1 ( 𝑥 = 𝐵 → ( 𝑥 ·ih 𝐴 ) = ( 𝐵 ·ih 𝐴 ) )
4 eqid ( 𝑥 ∈ ℋ ↦ ( 𝑥 ·ih 𝐴 ) ) = ( 𝑥 ∈ ℋ ↦ ( 𝑥 ·ih 𝐴 ) )
5 ovex ( 𝐵 ·ih 𝐴 ) ∈ V
6 3 4 5 fvmpt ( 𝐵 ∈ ℋ → ( ( 𝑥 ∈ ℋ ↦ ( 𝑥 ·ih 𝐴 ) ) ‘ 𝐵 ) = ( 𝐵 ·ih 𝐴 ) )
7 2 6 sylan9eq ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) → ( ( bra ‘ 𝐴 ) ‘ 𝐵 ) = ( 𝐵 ·ih 𝐴 ) )