Theorem ho2coi 31941

Description: Double composition of Hilbert space operators. (Contributed by NM, 1-Dec-2000.) (New usage is discouraged.)

Hypotheses

Ref	Expression
hods.1	⊢ 𝑅: ℋ⟶ ℋ
hods.2	⊢ 𝑆: ℋ⟶ ℋ
hods.3	⊢ 𝑇: ℋ⟶ ℋ

Assertion

Ref	Expression
ho2coi	⊢ (𝐴 ∈ ℋ → (((𝑅 ∘ 𝑆) ∘ 𝑇)‘𝐴) = (𝑅‘(𝑆‘(𝑇‘𝐴))))

Proof of Theorem ho2coi

Step	Hyp	Ref	Expression
1		hods.1	. . . 4 ⊢ 𝑅: ℋ⟶ ℋ
2		hods.2	. . . 4 ⊢ 𝑆: ℋ⟶ ℋ
3	1, 2	hocofi 31926	. . 3 ⊢ (𝑅 ∘ 𝑆): ℋ⟶ ℋ
4		hods.3	. . 3 ⊢ 𝑇: ℋ⟶ ℋ
5	3, 4	hocoi 31924	. 2 ⊢ (𝐴 ∈ ℋ → (((𝑅 ∘ 𝑆) ∘ 𝑇)‘𝐴) = ((𝑅 ∘ 𝑆)‘(𝑇‘𝐴)))
6	4	ffvelcdmi 7059	. . 3 ⊢ (𝐴 ∈ ℋ → (𝑇‘𝐴) ∈ ℋ)
7	1, 2	hocoi 31924	. . 3 ⊢ ((𝑇‘𝐴) ∈ ℋ → ((𝑅 ∘ 𝑆)‘(𝑇‘𝐴)) = (𝑅‘(𝑆‘(𝑇‘𝐴))))
8	6, 7	syl 17	. 2 ⊢ (𝐴 ∈ ℋ → ((𝑅 ∘ 𝑆)‘(𝑇‘𝐴)) = (𝑅‘(𝑆‘(𝑇‘𝐴))))
9	5, 8	eqtrd 2796	1 ⊢ (𝐴 ∈ ℋ → (((𝑅 ∘ 𝑆) ∘ 𝑇)‘𝐴) = (𝑅‘(𝑆‘(𝑇‘𝐴))))

Syntax hints:   → wi 4   = wceq 1559   ∈ wcel 2141   ∘ ccom 5647  ⟶wf 6512  ‘cfv 6516   ℋchba 31079

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1814  ax-4 1828  ax-5 1929  ax-6 1986  ax-7 2027  ax-8 2143  ax-9 2151  ax-10 2174  ax-11 2190  ax-12 2211  ax-ext 2733  ax-sep 5243  ax-nul 5253  ax-pr 5387

This theorem depends on definitions:  df-bi 209  df-an 400  df-or 859  df-3an 1099  df-tru 1562  df-fal 1572  df-ex 1799  df-nf 1803  df-sb 2090  df-mo 2565  df-eu 2595  df-clab 2740  df-cleq 2753  df-clel 2836  df-nfc 2910  df-ne 2957  df-ral 3076  df-rex 3086  df-rab 3414  df-v 3455  df-dif 3905  df-un 3907  df-in 3909  df-ss 3919  df-nul 4284  df-if 4478  df-sn 4580  df-pr 4582  df-op 4586  df-uni 4863  df-br 5098  df-opab 5160  df-id 5538  df-xp 5649  df-rel 5650  df-cnv 5651  df-co 5652  df-dm 5653  df-rn 5654  df-res 5655  df-ima 5656  df-iota 6472  df-fun 6518  df-fn 6519  df-f 6520  df-fv 6524

This theorem is referenced by:  pj2cocli  32365