Theorem isfxp 33132

Description: Property of being a fixed point. (Contributed by Thierry Arnoux, 18-Nov-2025.)

Hypotheses

Ref	Expression
fxpgaval.s	⊢ 𝑈 = (Base‘𝐺)
fxpgaval.a	⊢ (𝜑 → 𝐴 ∈ (𝐺 GrpAct 𝐶))
isfxp.x	⊢ (𝜑 → 𝑋 ∈ 𝐶)

Assertion

Ref	Expression
isfxp	⊢ (𝜑 → (𝑋 ∈ (𝐶FixPts𝐴) ↔ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑋) = 𝑋))

Distinct variable groups:   𝐴,𝑝   𝐺,𝑝   𝑈,𝑝   𝑋,𝑝

Allowed substitution hints:   𝜑(𝑝)   𝐶(𝑝)

Proof of Theorem isfxp

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		isfxp.x	. 2 ⊢ (𝜑 → 𝑋 ∈ 𝐶)
2		fxpgaval.s	. . . . 5 ⊢ 𝑈 = (Base‘𝐺)
3		fxpgaval.a	. . . . 5 ⊢ (𝜑 → 𝐴 ∈ (𝐺 GrpAct 𝐶))
4	2, 3	fxpgaval 33131	. . . 4 ⊢ (𝜑 → (𝐶FixPts𝐴) = {𝑥 ∈ 𝐶 ∣ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑥) = 𝑥})
5	4	eleq2d 2817	. . 3 ⊢ (𝜑 → (𝑋 ∈ (𝐶FixPts𝐴) ↔ 𝑋 ∈ {𝑥 ∈ 𝐶 ∣ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑥) = 𝑥}))
6		oveq2 7354	. . . . . 6 ⊢ (𝑥 = 𝑋 → (𝑝𝐴𝑥) = (𝑝𝐴𝑋))
7		id 22	. . . . . 6 ⊢ (𝑥 = 𝑋 → 𝑥 = 𝑋)
8	6, 7	eqeq12d 2747	. . . . 5 ⊢ (𝑥 = 𝑋 → ((𝑝𝐴𝑥) = 𝑥 ↔ (𝑝𝐴𝑋) = 𝑋))
9	8	ralbidv 3155	. . . 4 ⊢ (𝑥 = 𝑋 → (∀𝑝 ∈ 𝑈 (𝑝𝐴𝑥) = 𝑥 ↔ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑋) = 𝑋))
10	9	elrab 3647	. . 3 ⊢ (𝑋 ∈ {𝑥 ∈ 𝐶 ∣ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑥) = 𝑥} ↔ (𝑋 ∈ 𝐶 ∧ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑋) = 𝑋))
11	5, 10	bitrdi 287	. 2 ⊢ (𝜑 → (𝑋 ∈ (𝐶FixPts𝐴) ↔ (𝑋 ∈ 𝐶 ∧ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑋) = 𝑋)))
12	1, 11	mpbirand 707	1 ⊢ (𝜑 → (𝑋 ∈ (𝐶FixPts𝐴) ↔ ∀𝑝 ∈ 𝑈 (𝑝𝐴𝑋) = 𝑋))

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1541   ∈ wcel 2111  ∀wral 3047  {crab 3395  ‘cfv 6481  (class class class)co 7346  Basecbs 17117   GrpAct cga 19199  FixPtscfxp 33127

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2113  ax-9 2121  ax-10 2144  ax-11 2160  ax-12 2180  ax-ext 2703  ax-sep 5234  ax-nul 5244  ax-pow 5303  ax-pr 5370  ax-un 7668

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1544  df-fal 1554  df-ex 1781  df-nf 1785  df-sb 2068  df-mo 2535  df-eu 2564  df-clab 2710  df-cleq 2723  df-clel 2806  df-nfc 2881  df-ne 2929  df-ral 3048  df-rex 3057  df-rab 3396  df-v 3438  df-sbc 3742  df-csb 3851  df-dif 3905  df-un 3907  df-in 3909  df-ss 3919  df-nul 4284  df-if 4476  df-pw 4552  df-sn 4577  df-pr 4579  df-op 4583  df-uni 4860  df-br 5092  df-opab 5154  df-id 5511  df-xp 5622  df-rel 5623  df-cnv 5624  df-co 5625  df-dm 5626  df-rn 5627  df-iota 6437  df-fun 6483  df-fn 6484  df-f 6485  df-fv 6489  df-ov 7349  df-oprab 7350  df-mpo 7351  df-map 8752  df-ga 19200  df-fxp 33128

This theorem is referenced by:  fxpsubm  33136  fxpsubg  33137  fxpsubrg  33138  fxpsdrg  33139  issply  33579