finextfldext - Mathbox for Thierry Arnoux

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Theorem finextfldext 33808

Description: A finite field extension is a field extension. (Contributed by Thierry Arnoux, 10-Jan-2026.)

**Hypothesis**
Ref	Expression
finextfldext.1	⊢ (𝜑 → 𝐸/_FinExt𝐹)

**Assertion**
Ref	Expression
finextfldext	⊢ (𝜑 → 𝐸/_FldExt𝐹)

Proof of Theorem finextfldext Dummy variables 𝑒 𝑓 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		finextfldext.1	. . 3 ⊢ (𝜑 → 𝐸/_FinExt𝐹)
2		df-finext 33787	. . . . . . 7 ⊢ /_FinExt = {⟨𝑒, 𝑓⟩ ∣ (𝑒/_FldExt𝑓 ∧ (𝑒[:]𝑓) ∈ ℕ₀)}
3	2	relopabiv 5776	. . . . . 6 ⊢ Rel /_FinExt
4	3	brrelex1i 5687	. . . . 5 ⊢ (𝐸/_FinExt𝐹 → 𝐸 ∈ V)
5	1, 4	syl 17	. . . 4 ⊢ (𝜑 → 𝐸 ∈ V)
6	3	brrelex2i 5688	. . . . 5 ⊢ (𝐸/_FinExt𝐹 → 𝐹 ∈ V)
7	1, 6	syl 17	. . . 4 ⊢ (𝜑 → 𝐹 ∈ V)
8		breq12 5090	. . . . . 6 ⊢ ((𝑒 = 𝐸 ∧ 𝑓 = 𝐹) → (𝑒/_FldExt𝑓 ↔ 𝐸/_FldExt𝐹))
9		oveq12 7376	. . . . . . 7 ⊢ ((𝑒 = 𝐸 ∧ 𝑓 = 𝐹) → (𝑒[:]𝑓) = (𝐸[:]𝐹))
10	9	eleq1d 2821	. . . . . 6 ⊢ ((𝑒 = 𝐸 ∧ 𝑓 = 𝐹) → ((𝑒[:]𝑓) ∈ ℕ₀ ↔ (𝐸[:]𝐹) ∈ ℕ₀))
11	8, 10	anbi12d 633	. . . . 5 ⊢ ((𝑒 = 𝐸 ∧ 𝑓 = 𝐹) → ((𝑒/_FldExt𝑓 ∧ (𝑒[:]𝑓) ∈ ℕ₀) ↔ (𝐸/_FldExt𝐹 ∧ (𝐸[:]𝐹) ∈ ℕ₀)))
12	11, 2	brabga 5489	. . . 4 ⊢ ((𝐸 ∈ V ∧ 𝐹 ∈ V) → (𝐸/_FinExt𝐹 ↔ (𝐸/_FldExt𝐹 ∧ (𝐸[:]𝐹) ∈ ℕ₀)))
13	5, 7, 12	syl2anc 585	. . 3 ⊢ (𝜑 → (𝐸/_FinExt𝐹 ↔ (𝐸/_FldExt𝐹 ∧ (𝐸[:]𝐹) ∈ ℕ₀)))
14	1, 13	mpbid 232	. 2 ⊢ (𝜑 → (𝐸/_FldExt𝐹 ∧ (𝐸[:]𝐹) ∈ ℕ₀))
15	14	simpld 494	1 ⊢ (𝜑 → 𝐸/_FldExt𝐹)

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 = wceq 1542 ∈ wcel 2114 Vcvv 3429 class class class wbr 5085 (class class class)co 7367 ℕ₀cn0 12437 /_FldExtcfldext 33782 /_FinExtcfinext 33783 [:]cextdg 33784

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-ext 2708 ax-sep 5231 ax-pr 5375

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-sb 2069 df-clab 2715 df-cleq 2728 df-clel 2811 df-ral 3052 df-rex 3062 df-rab 3390 df-v 3431 df-dif 3892 df-un 3894 df-in 3896 df-ss 3906 df-nul 4274 df-if 4467 df-sn 4568 df-pr 4570 df-op 4574 df-uni 4851 df-br 5086 df-opab 5148 df-xp 5637 df-rel 5638 df-iota 6454 df-fv 6506 df-ov 7370 df-finext 33787

This theorem is referenced by: finextalg 33842

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