dpval - Mathbox for Thierry Arnoux

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Theorem dpval 32981

Description: Define the value of the decimal point operator. See df-dp 32980. (Contributed by David A. Wheeler, 15-May-2015.)

**Assertion**
Ref	Expression
dpval	⊢ ((𝐴 ∈ ℕ₀ ∧ 𝐵 ∈ ℝ) → (𝐴.𝐵) = _𝐴𝐵)

Proof of Theorem dpval Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		df-dp2 32963	. . 3 ⊢ _𝑥𝑦 = (𝑥 + (𝑦 / ;10))
2		oveq1 7375	. . 3 ⊢ (𝑥 = 𝐴 → (𝑥 + (𝑦 / ;10)) = (𝐴 + (𝑦 / ;10)))
3	1, 2	eqtrid 2784	. 2 ⊢ (𝑥 = 𝐴 → _𝑥𝑦 = (𝐴 + (𝑦 / ;10)))
4		oveq1 7375	. . . 4 ⊢ (𝑦 = 𝐵 → (𝑦 / ;10) = (𝐵 / ;10))
5	4	oveq2d 7384	. . 3 ⊢ (𝑦 = 𝐵 → (𝐴 + (𝑦 / ;10)) = (𝐴 + (𝐵 / ;10)))
6		df-dp2 32963	. . 3 ⊢ _𝐴𝐵 = (𝐴 + (𝐵 / ;10))
7	5, 6	eqtr4di 2790	. 2 ⊢ (𝑦 = 𝐵 → (𝐴 + (𝑦 / ;10)) = _𝐴𝐵)
8		df-dp 32980	. 2 ⊢ . = (𝑥 ∈ ℕ₀, 𝑦 ∈ ℝ ↦ _𝑥𝑦)
9	6	ovexi 7402	. 2 ⊢ _𝐴𝐵 ∈ V
10	3, 7, 8, 9	ovmpo 7528	1 ⊢ ((𝐴 ∈ ℕ₀ ∧ 𝐵 ∈ ℝ) → (𝐴.𝐵) = _𝐴𝐵)

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 395 = wceq 1542 ∈ wcel 2114 (class class class)co 7368 ℝcr 11037 0cc0 11038 1c1 11039 + caddc 11041 / cdiv 11806 ℕ₀cn0 12413 cdc 12619 cdp2 32962 .cdp 32979

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1912 ax-6 1969 ax-7 2010 ax-8 2116 ax-9 2124 ax-10 2147 ax-11 2163 ax-12 2185 ax-ext 2709 ax-sep 5243 ax-nul 5253 ax-pr 5379

This theorem depends on definitions: df-bi 207 df-an 396 df-or 849 df-3an 1089 df-tru 1545 df-fal 1555 df-ex 1782 df-nf 1786 df-sb 2069 df-mo 2540 df-eu 2570 df-clab 2716 df-cleq 2729 df-clel 2812 df-nfc 2886 df-ne 2934 df-ral 3053 df-rex 3063 df-rab 3402 df-v 3444 df-sbc 3743 df-dif 3906 df-un 3908 df-in 3910 df-ss 3920 df-nul 4288 df-if 4482 df-sn 4583 df-pr 4585 df-op 4589 df-uni 4866 df-br 5101 df-opab 5163 df-id 5527 df-xp 5638 df-rel 5639 df-cnv 5640 df-co 5641 df-dm 5642 df-iota 6456 df-fun 6502 df-fv 6508 df-ov 7371 df-oprab 7372 df-mpo 7373 df-dp2 32963 df-dp 32980

This theorem is referenced by: dpcl 32982 dpfrac1 32983 dpval2 32984 dpmul1000 32990 dpadd2 33001

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