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Theorem isga 19418
Description: The predicate "is a (left) group action". The group 𝐺 is said to act on the base set 𝑌 of the action, which is not assumed to have any special properties. There is a related notion of right group action, but as the Wikipedia article explains, it is not mathematically interesting. The way actions are usually thought of is that each element 𝑔 of 𝐺 is a permutation of the elements of 𝑌 (see gapm 19433). Since group theory was classically about symmetry groups, it is therefore likely that the notion of group action was useful even in early group theory. (Contributed by Jeff Hankins, 10-Aug-2009.) (Revised by Mario Carneiro, 13-Jan-2015.)
Hypotheses
Ref Expression
isga.1 𝑋 = (Base‘𝐺)
isga.2 + = (+g𝐺)
isga.3 0 = (0g𝐺)
Assertion
Ref Expression
isga ( ∈ (𝐺 GrpAct 𝑌) ↔ ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) ∧ ( :(𝑋 × 𝑌)⟶𝑌 ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))))
Distinct variable groups:   𝑥,𝑦,𝑧,𝐺   𝑦,𝑋,𝑧   𝑥,𝑌,𝑦,𝑧   𝑥, ,𝑦,𝑧
Allowed substitution hints:   + (𝑥, 𝑦, 𝑧)   𝑋(𝑥)   0 (𝑥, 𝑦, 𝑧)

Proof of Theorem isga
Dummy variables 𝑔 𝑏 𝑚 𝑠 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-ga 19417 . . 3 GrpAct = (𝑔 ∈ Grp, 𝑠 ∈ V ↦ (Base‘𝑔) / 𝑏{𝑚 ∈ (𝑠m (𝑏 × 𝑠)) ∣ ∀𝑥𝑠 (((0g𝑔)𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))})
21elmpocl 7655 . 2 ( ∈ (𝐺 GrpAct 𝑌) → (𝐺 ∈ Grp ∧ 𝑌 ∈ V))
3 fvexd 6893 . . . . . . 7 ((𝑔 = 𝐺𝑠 = 𝑌) → (Base‘𝑔) ∈ V)
4 simplr 781 . . . . . . . . 9 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → 𝑠 = 𝑌)
5 id 23 . . . . . . . . . . 11 (𝑏 = (Base‘𝑔) → 𝑏 = (Base‘𝑔))
6 simpl 488 . . . . . . . . . . . . 13 ((𝑔 = 𝐺𝑠 = 𝑌) → 𝑔 = 𝐺)
76fveq2d 6882 . . . . . . . . . . . 12 ((𝑔 = 𝐺𝑠 = 𝑌) → (Base‘𝑔) = (Base‘𝐺))
8 isga.1 . . . . . . . . . . . 12 𝑋 = (Base‘𝐺)
97, 8eqtr4di 2813 . . . . . . . . . . 11 ((𝑔 = 𝐺𝑠 = 𝑌) → (Base‘𝑔) = 𝑋)
105, 9sylan9eqr 2817 . . . . . . . . . 10 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → 𝑏 = 𝑋)
1110, 4xpeq12d 5686 . . . . . . . . 9 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (𝑏 × 𝑠) = (𝑋 × 𝑌))
124, 11oveq12d 7431 . . . . . . . 8 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (𝑠m (𝑏 × 𝑠)) = (𝑌m (𝑋 × 𝑌)))
13 simpll 779 . . . . . . . . . . . . . 14 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → 𝑔 = 𝐺)
1413fveq2d 6882 . . . . . . . . . . . . 13 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (0g𝑔) = (0g𝐺))
15 isga.3 . . . . . . . . . . . . 13 0 = (0g𝐺)
1614, 15eqtr4di 2813 . . . . . . . . . . . 12 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (0g𝑔) = 0 )
1716oveq1d 7428 . . . . . . . . . . 11 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → ((0g𝑔)𝑚𝑥) = ( 0 𝑚𝑥))
1817eqeq1d 2762 . . . . . . . . . 10 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (((0g𝑔)𝑚𝑥) = 𝑥 ↔ ( 0 𝑚𝑥) = 𝑥))
1913fveq2d 6882 . . . . . . . . . . . . . . . 16 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (+g𝑔) = (+g𝐺))
20 isga.2 . . . . . . . . . . . . . . . 16 + = (+g𝐺)
2119, 20eqtr4di 2813 . . . . . . . . . . . . . . 15 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (+g𝑔) = + )
2221oveqd 7430 . . . . . . . . . . . . . 14 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (𝑦(+g𝑔)𝑧) = (𝑦 + 𝑧))
2322oveq1d 7428 . . . . . . . . . . . . 13 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → ((𝑦(+g𝑔)𝑧)𝑚𝑥) = ((𝑦 + 𝑧)𝑚𝑥))
2423eqeq1d 2762 . . . . . . . . . . . 12 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)) ↔ ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))))
2510, 24raleqbidv 3334 . . . . . . . . . . 11 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (∀𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)) ↔ ∀𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))))
2610, 25raleqbidv 3334 . . . . . . . . . 10 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)) ↔ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))))
2718, 26anbi12d 644 . . . . . . . . 9 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → ((((0g𝑔)𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))) ↔ (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))))
284, 27raleqbidv 3334 . . . . . . . 8 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → (∀𝑥𝑠 (((0g𝑔)𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))) ↔ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))))
2912, 28rabeqbidv 3429 . . . . . . 7 (((𝑔 = 𝐺𝑠 = 𝑌) ∧ 𝑏 = (Base‘𝑔)) → {𝑚 ∈ (𝑠m (𝑏 × 𝑠)) ∣ ∀𝑥𝑠 (((0g𝑔)𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))} = {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))})
303, 29csbied 3883 . . . . . 6 ((𝑔 = 𝐺𝑠 = 𝑌) → (Base‘𝑔) / 𝑏{𝑚 ∈ (𝑠m (𝑏 × 𝑠)) ∣ ∀𝑥𝑠 (((0g𝑔)𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑏𝑧𝑏 ((𝑦(+g𝑔)𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))} = {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))})
31 ovex 7446 . . . . . . 7 (𝑌m (𝑋 × 𝑌)) ∈ V
3231rabex 5303 . . . . . 6 {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))} ∈ V
3330, 1, 32ovmpoa 7568 . . . . 5 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → (𝐺 GrpAct 𝑌) = {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))})
3433eleq2d 2846 . . . 4 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → ( ∈ (𝐺 GrpAct 𝑌) ↔ ∈ {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))}))
35 oveq 7419 . . . . . . . 8 (𝑚 = → ( 0 𝑚𝑥) = ( 0 𝑥))
3635eqeq1d 2762 . . . . . . 7 (𝑚 = → (( 0 𝑚𝑥) = 𝑥 ↔ ( 0 𝑥) = 𝑥))
37 oveq 7419 . . . . . . . . 9 (𝑚 = → ((𝑦 + 𝑧)𝑚𝑥) = ((𝑦 + 𝑧) 𝑥))
38 oveq 7419 . . . . . . . . . 10 (𝑚 = → (𝑦𝑚(𝑧𝑚𝑥)) = (𝑦 (𝑧𝑚𝑥)))
39 oveq 7419 . . . . . . . . . . 11 (𝑚 = → (𝑧𝑚𝑥) = (𝑧 𝑥))
4039oveq2d 7429 . . . . . . . . . 10 (𝑚 = → (𝑦 (𝑧𝑚𝑥)) = (𝑦 (𝑧 𝑥)))
4138, 40eqtrd 2795 . . . . . . . . 9 (𝑚 = → (𝑦𝑚(𝑧𝑚𝑥)) = (𝑦 (𝑧 𝑥)))
4237, 41eqeq12d 2776 . . . . . . . 8 (𝑚 = → (((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)) ↔ ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))
43422ralbidv 3226 . . . . . . 7 (𝑚 = → (∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)) ↔ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))
4436, 43anbi12d 644 . . . . . 6 (𝑚 = → ((( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))) ↔ (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥)))))
4544ralbidv 3185 . . . . 5 (𝑚 = → (∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥))) ↔ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥)))))
4645elrab 3645 . . . 4 ( ∈ {𝑚 ∈ (𝑌m (𝑋 × 𝑌)) ∣ ∀𝑥𝑌 (( 0 𝑚𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧)𝑚𝑥) = (𝑦𝑚(𝑧𝑚𝑥)))} ↔ ( ∈ (𝑌m (𝑋 × 𝑌)) ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥)))))
4734, 46bitrdi 290 . . 3 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → ( ∈ (𝐺 GrpAct 𝑌) ↔ ( ∈ (𝑌m (𝑋 × 𝑌)) ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))))
48 simpr 490 . . . . 5 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → 𝑌 ∈ V)
498fvexi 6892 . . . . . 6 𝑋 ∈ V
50 xpexg 7749 . . . . . 6 ((𝑋 ∈ V ∧ 𝑌 ∈ V) → (𝑋 × 𝑌) ∈ V)
5149, 48, 50sylancr 599 . . . . 5 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → (𝑋 × 𝑌) ∈ V)
5248, 51elmapd 8839 . . . 4 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → ( ∈ (𝑌m (𝑋 × 𝑌)) ↔ :(𝑋 × 𝑌)⟶𝑌))
5352anbi1d 643 . . 3 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → (( ∈ (𝑌m (𝑋 × 𝑌)) ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥)))) ↔ ( :(𝑋 × 𝑌)⟶𝑌 ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))))
5447, 53bitrd 282 . 2 ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) → ( ∈ (𝐺 GrpAct 𝑌) ↔ ( :(𝑋 × 𝑌)⟶𝑌 ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))))
552, 54biadanii 834 1 ( ∈ (𝐺 GrpAct 𝑌) ↔ ((𝐺 ∈ Grp ∧ 𝑌 ∈ V) ∧ ( :(𝑋 × 𝑌)⟶𝑌 ∧ ∀𝑥𝑌 (( 0 𝑥) = 𝑥 ∧ ∀𝑦𝑋𝑧𝑋 ((𝑦 + 𝑧) 𝑥) = (𝑦 (𝑧 𝑥))))))
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  wb 209  wa 401   = wceq 1570  wcel 2145  wral 3076  {crab 3412  Vcvv 3450  csb 3847   × cxp 5653  wf 6529  cfv 6533  (class class class)co 7413  m cmap 8826  Basecbs 17301  +gcplusg 17342  0gc0g 17524  Grpcgrp 19057   GrpAct cga 19416
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-10 2178  ax-11 2194  ax-12 2213  ax-ext 2732  ax-sep 5251  ax-nul 5263  ax-pow 5330  ax-pr 5398  ax-un 7736
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1813  df-nf 1817  df-sb 2100  df-mo 2564  df-eu 2594  df-clab 2739  df-cleq 2752  df-clel 2835  df-nfc 2909  df-ne 2956  df-ral 3077  df-rex 3087  df-rab 3413  df-v 3452  df-sbc 3740  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-nul 4280  df-if 4483  df-pw 4559  df-sn 4585  df-pr 4587  df-op 4591  df-uni 4868  df-br 5104  df-opab 5168  df-id 5550  df-xp 5661  df-rel 5662  df-cnv 5663  df-co 5664  df-dm 5665  df-rn 5666  df-iota 6489  df-fun 6535  df-fn 6536  df-f 6537  df-fv 6541  df-ov 7416  df-oprab 7417  df-mpo 7418  df-map 8828  df-ga 19417
This theorem is used by:  gagrp  19419  gaset  19420  gagrpid  19421  gaf  19422  gaass  19424  ga0  19425  gaid  19426  subgga  19427  gass  19428  gasubg  19429  lactghmga  19532  sylow1lem2  19726  sylow2blem2  19748  sylow3lem1  19754  conjga  33610  mplvrpmga  34055
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