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Description: Dirac bra-ket associative law ( | A >. <. B | ) ( | C >. <. D | ) = ( ( | A >. <. B | ) | C >. ) <. D | . (Contributed by NM, 30-May-2006) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | kbass5 | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) = ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | kbval | ⊢ ( ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ∧ 𝑥 ∈ ℋ ) → ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) | |
| 2 | 1 | 3expa | ⊢ ( ( ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) |
| 3 | 2 | adantll | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) |
| 4 | 3 | fveq2d | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) ) = ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) ) |
| 5 | simplll | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → 𝐴 ∈ ℋ ) | |
| 6 | simpllr | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → 𝐵 ∈ ℋ ) | |
| 7 | simpr | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → 𝑥 ∈ ℋ ) | |
| 8 | simplrr | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → 𝐷 ∈ ℋ ) | |
| 9 | hicl | ⊢ ( ( 𝑥 ∈ ℋ ∧ 𝐷 ∈ ℋ ) → ( 𝑥 ·ih 𝐷 ) ∈ ℂ ) | |
| 10 | 7 8 9 | syl2anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( 𝑥 ·ih 𝐷 ) ∈ ℂ ) |
| 11 | simplrl | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → 𝐶 ∈ ℋ ) | |
| 12 | hvmulcl | ⊢ ( ( ( 𝑥 ·ih 𝐷 ) ∈ ℂ ∧ 𝐶 ∈ ℋ ) → ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ∈ ℋ ) | |
| 13 | 10 11 12 | syl2anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ∈ ℋ ) |
| 14 | kbval | ⊢ ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ∧ ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) = ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) ) | |
| 15 | 5 6 13 14 | syl3anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ) = ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) ) |
| 16 | 4 15 | eqtrd | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) ) = ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) ) |
| 17 | kbop | ⊢ ( ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) → ( 𝐶 ketbra 𝐷 ) : ℋ ⟶ ℋ ) | |
| 18 | 17 | adantl | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( 𝐶 ketbra 𝐷 ) : ℋ ⟶ ℋ ) |
| 19 | fvco3 | ⊢ ( ( ( 𝐶 ketbra 𝐷 ) : ℋ ⟶ ℋ ∧ 𝑥 ∈ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) ) ) | |
| 20 | 18 19 | sylan | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( 𝐴 ketbra 𝐵 ) ‘ ( ( 𝐶 ketbra 𝐷 ) ‘ 𝑥 ) ) ) |
| 21 | kbval | ⊢ ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ∧ 𝐶 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) = ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) | |
| 22 | 5 6 11 21 | syl3anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) = ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) |
| 23 | 22 | oveq2d | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) ) |
| 24 | kbop | ⊢ ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) → ( 𝐴 ketbra 𝐵 ) : ℋ ⟶ ℋ ) | |
| 25 | 24 | ffvelcdmda | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ 𝐶 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ∈ ℋ ) |
| 26 | 25 | adantrr | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ∈ ℋ ) |
| 27 | 26 | adantr | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ∈ ℋ ) |
| 28 | kbval | ⊢ ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ∈ ℋ ∧ 𝐷 ∈ ℋ ∧ 𝑥 ∈ ℋ ) → ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ) ) | |
| 29 | 27 8 7 28 | syl3anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ) ) |
| 30 | ax-his3 | ⊢ ( ( ( 𝑥 ·ih 𝐷 ) ∈ ℂ ∧ 𝐶 ∈ ℋ ∧ 𝐵 ∈ ℋ ) → ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) = ( ( 𝑥 ·ih 𝐷 ) · ( 𝐶 ·ih 𝐵 ) ) ) | |
| 31 | 10 11 6 30 | syl3anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) = ( ( 𝑥 ·ih 𝐷 ) · ( 𝐶 ·ih 𝐵 ) ) ) |
| 32 | 31 | oveq1d | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) = ( ( ( 𝑥 ·ih 𝐷 ) · ( 𝐶 ·ih 𝐵 ) ) ·ℎ 𝐴 ) ) |
| 33 | hicl | ⊢ ( ( 𝐶 ∈ ℋ ∧ 𝐵 ∈ ℋ ) → ( 𝐶 ·ih 𝐵 ) ∈ ℂ ) | |
| 34 | 11 6 33 | syl2anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( 𝐶 ·ih 𝐵 ) ∈ ℂ ) |
| 35 | ax-hvmulass | ⊢ ( ( ( 𝑥 ·ih 𝐷 ) ∈ ℂ ∧ ( 𝐶 ·ih 𝐵 ) ∈ ℂ ∧ 𝐴 ∈ ℋ ) → ( ( ( 𝑥 ·ih 𝐷 ) · ( 𝐶 ·ih 𝐵 ) ) ·ℎ 𝐴 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) ) | |
| 36 | 10 34 5 35 | syl3anc | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( 𝑥 ·ih 𝐷 ) · ( 𝐶 ·ih 𝐵 ) ) ·ℎ 𝐴 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) ) |
| 37 | 32 36 | eqtrd | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) = ( ( 𝑥 ·ih 𝐷 ) ·ℎ ( ( 𝐶 ·ih 𝐵 ) ·ℎ 𝐴 ) ) ) |
| 38 | 23 29 37 | 3eqtr4d | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) = ( ( ( ( 𝑥 ·ih 𝐷 ) ·ℎ 𝐶 ) ·ih 𝐵 ) ·ℎ 𝐴 ) ) |
| 39 | 16 20 38 | 3eqtr4d | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) ∧ 𝑥 ∈ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) ) |
| 40 | 39 | ralrimiva | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ∀ 𝑥 ∈ ℋ ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) ) |
| 41 | fco | ⊢ ( ( ( 𝐴 ketbra 𝐵 ) : ℋ ⟶ ℋ ∧ ( 𝐶 ketbra 𝐷 ) : ℋ ⟶ ℋ ) → ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) : ℋ ⟶ ℋ ) | |
| 42 | 24 17 41 | syl2an | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) : ℋ ⟶ ℋ ) |
| 43 | kbop | ⊢ ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ∈ ℋ ∧ 𝐷 ∈ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) : ℋ ⟶ ℋ ) | |
| 44 | 25 43 | sylan | ⊢ ( ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ 𝐶 ∈ ℋ ) ∧ 𝐷 ∈ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) : ℋ ⟶ ℋ ) |
| 45 | 44 | anasss | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) : ℋ ⟶ ℋ ) |
| 46 | ffn | ⊢ ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) : ℋ ⟶ ℋ → ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) Fn ℋ ) | |
| 47 | ffn | ⊢ ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) : ℋ ⟶ ℋ → ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) Fn ℋ ) | |
| 48 | eqfnfv | ⊢ ( ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) Fn ℋ ∧ ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) Fn ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) = ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ↔ ∀ 𝑥 ∈ ℋ ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) ) ) | |
| 49 | 46 47 48 | syl2an | ⊢ ( ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) : ℋ ⟶ ℋ ∧ ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) : ℋ ⟶ ℋ ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) = ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ↔ ∀ 𝑥 ∈ ℋ ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) ) ) |
| 50 | 42 45 49 | syl2anc | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) = ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ↔ ∀ 𝑥 ∈ ℋ ( ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) ‘ 𝑥 ) = ( ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ‘ 𝑥 ) ) ) |
| 51 | 40 50 | mpbird | ⊢ ( ( ( 𝐴 ∈ ℋ ∧ 𝐵 ∈ ℋ ) ∧ ( 𝐶 ∈ ℋ ∧ 𝐷 ∈ ℋ ) ) → ( ( 𝐴 ketbra 𝐵 ) ∘ ( 𝐶 ketbra 𝐷 ) ) = ( ( ( 𝐴 ketbra 𝐵 ) ‘ 𝐶 ) ketbra 𝐷 ) ) |