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sub_abelian_cent2: B \subset A -> C \subset A -> B \subset 'C(C). Proof. by move=> sBA; move/sub_abelian_cent; apply: subset_trans. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
sub_abelian_cent2
sub_abelian_norm: C \subset A -> A \subset 'N(C). Proof. by move=> sCA; rewrite cents_norm ?sub_abelian_cent. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
sub_abelian_norm
sub_abelian_normal: (C \subset A) = (C <| A). Proof. by rewrite /normal; case sHG: (C \subset A); rewrite // sub_abelian_norm. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
sub_abelian_normal
maxgroupA gP := maxset (fun A => group_set A && gP <<A>>%G) A.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
maxgroup
mingroupA gP := minset (fun A => group_set A && gP <<A>>%G) A. Variable gP : pred {group gT}. Arguments gP _%_G.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
mingroup
ex_maxgroup: (exists G, gP G) -> {G : {group gT} | maxgroup G gP}. Proof. move=> exP; have [A maxA]: {A | maxgroup A gP}. apply: ex_maxset; case: exP => G gPG. by exists (G : {set gT}); rewrite groupP genGidG. by exists <<A>>%G; rewrite /= gen_set_id; case/andP: (maxsetp maxA). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
ex_maxgroup
ex_mingroup: (exists G, gP G) -> {G : {group gT} | mingroup G gP}. Proof. move=> exP; have [A minA]: {A | mingroup A gP}. apply: ex_minset; case: exP => G gPG. by exists (G : {set gT}); rewrite groupP genGidG. by exists <<A>>%G; rewrite /= gen_set_id; case/andP: (minsetp minA). Qed. Variable G : {group gT}.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
ex_mingroup
mingroupP: reflect (gP G /\ forall H, gP H -> H \subset G -> H :=: G) (mingroup G gP). Proof. apply: (iffP minsetP); rewrite /= groupP genGidG /= => [] [-> minG]. by split=> // H gPH sGH; apply: minG; rewrite // groupP genGidG. by split=> // A; case/andP=> gA gPA; rewrite -(gen_set_id gA); apply: minG. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
mingroupP
maxgroupP: reflect (gP G /\ forall H, gP H -> G \subset H -> H :=: G) (maxgroup G gP). Proof. apply: (iffP maxsetP); rewrite /= groupP genGidG /= => [] [-> maxG]. by split=> // H gPH sGH; apply: maxG; rewrite // groupP genGidG. by split=> // A; case/andP=> gA gPA; rewrite -(gen_set_id gA); apply: maxG. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
maxgroupP
maxgroupp: maxgroup G gP -> gP G. Proof. by case/maxgroupP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
maxgroupp
mingroupp: mingroup G gP -> gP G. Proof. by case/mingroupP. Qed. Hypothesis gPG : gP G.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
mingroupp
maxgroup_exists: {H : {group gT} | maxgroup H gP & G \subset H}. Proof. have [A maxA sGA]: {A | maxgroup A gP & G \subset A}. by apply: maxset_exists; rewrite groupP genGidG. by exists <<A>>%G; rewrite /= gen_set_id; case/andP: (maxsetp maxA). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
maxgroup_exists
mingroup_exists: {H : {group gT} | mingroup H gP & H \subset G}. Proof. have [A maxA sGA]: {A | mingroup A gP & A \subset G}. by apply: minset_exists; rewrite groupP genGidG. by exists <<A>>%G; rewrite /= gen_set_id; case/andP: (minsetp maxA). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq choice", "From mathcomp Require Import fintype div path tuple bigop prime finset", "From mathcomp Require Export monoid" ]
fingroup/fingroup.v
mingroup_exists
partial_productA B := if A == 1 then B else if B == 1 then A else if [&& group_set A, group_set B & B \subset 'N(A)] then A * B else set0.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
partial_product
semidirect_productA B := if A :&: B \subset 1%G then partial_product A B else set0.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
semidirect_product
central_productA B := if B \subset 'C(A) then partial_product A B else set0.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
central_product
direct_productA B := if A :&: B \subset 1%G then central_product A B else set0.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
direct_product
complements_to_inA B := [set K : {group gT} | A :&: K == 1 & A * K == B].
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
complements_to_in
splits_overB A := complements_to_in A B != set0.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
splits_over
remgrA B x := repr (A :* x :&: B).
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgr
divgrA B x := x * (remgr A B x)^-1.
Definition
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgr
pprod:= (partial_product _).
Notation
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprod
sdprod:= (semidirect_product _).
Notation
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod
cprod:= (central_product _).
Notation
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprod
dprod:= (direct_product _).
Notation
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
dprod
pprod1g: left_id 1 pprod. Proof. by move=> A; rewrite /pprod eqxx. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprod1g
pprodg1: right_id 1 pprod. Proof. by move=> A; rewrite /pprod eqxx; case: eqP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodg1
are_groupsA B : Prop := AreGroups K H of A = K & B = H.
Variant
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
are_groups
group_not0G : set0 <> G. Proof. by move/setP/(_ 1); rewrite inE group1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
group_not0
mulg0: right_zero (@set0 gT) mul. Proof. by move=> A; apply/setP=> x; rewrite inE; apply/imset2P=> [[y z]]; rewrite inE. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
mulg0
mul0g: left_zero (@set0 gT) mul. Proof. by move=> A; apply/setP=> x; rewrite inE; apply/imset2P=> [[y z]]; rewrite inE. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
mul0g
pprodPA B G : pprod A B = G -> [/\ are_groups A B, A * B = G & B \subset 'N(A)]. Proof. have Gnot0 := @group_not0 G; rewrite /pprod; do 2?case: eqP => [-> ->| _]. - by rewrite mul1g norms1; split; first exists 1%G G. - by rewrite mulg1 sub1G; split; first exists G 1%G. by case: and3P => // [[gA gB ->]]; split; first exists (Group gA) (Group gB). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodP
pprodEK H : H \subset 'N(K) -> pprod K H = K * H. Proof. move=> nKH; rewrite /pprod nKH !groupP /=. by do 2?case: eqP => [-> | _]; rewrite ?mulg1 ?mul1g. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodE
pprodEYK H : H \subset 'N(K) -> pprod K H = K <*> H. Proof. by move=> nKH; rewrite pprodE ?norm_joinEr. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodEY
pprodWA B G : pprod A B = G -> A * B = G. Proof. by case/pprodP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodW
pprodWCA B G : pprod A B = G -> B * A = G. Proof. by case/pprodP=> _ <- /normC. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodWC
pprodWYA B G : pprod A B = G -> A <*> B = G. Proof. by case/pprodP=> [[K H -> ->] <- /norm_joinEr]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodWY
pprodJA B x : pprod A B :^ x = pprod (A :^ x) (B :^ x). Proof. rewrite /pprod !conjsg_eq1 !group_setJ normJ conjSg -conjsMg. by do 3?case: ifP => // _; apply: conj0g. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
pprodJ
remgrMlK B x y : y \in K -> remgr K B (y * x) = remgr K B x. Proof. by move=> Ky; rewrite {1}/remgr rcosetM rcoset_id. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgrMl
remgrPK B x : (remgr K B x \in K :* x :&: B) = (x \in K * B). Proof. set y := _ x; apply/idP/mulsgP=> [|[g b Kg Bb x_gb]]. rewrite inE rcoset_sym mem_rcoset => /andP[Kxy' By]. by exists (x * y^-1) y; rewrite ?mulgKV. by apply: (mem_repr b); rewrite inE rcoset_sym mem_rcoset x_gb mulgK Kg. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgrP
remgr1K H x : x \in K -> remgr K H x = 1. Proof. by move=> Kx; rewrite /remgr rcoset_id ?repr_group. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgr1
divgr_eqA B x : x = divgr A B x * remgr A B x. Proof. by rewrite mulgKV. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgr_eq
divgrMlK B x y : x \in K -> divgr K B (x * y) = x * divgr K B y. Proof. by move=> Hx; rewrite /divgr remgrMl ?mulgA. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgrMl
divgr_idK H x : x \in K -> divgr K H x = x. Proof. by move=> Kx; rewrite /divgr remgr1 // invg1 mulg1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgr_id
mem_remgrK B x : x \in K * B -> remgr K B x \in B. Proof. by rewrite -remgrP => /setIP[]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
mem_remgr
mem_divgrK B x : x \in K * B -> divgr K B x \in K. Proof. by rewrite -remgrP inE rcoset_sym mem_rcoset => /andP[]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
mem_divgr
remgr_idx : x \in H -> remgr K H x = x. Proof. move=> Hx; apply/eqP; rewrite eq_mulgV1 (sameP eqP set1gP) -tiKH inE. rewrite -mem_rcoset groupMr ?groupV // -in_setI remgrP. by apply: subsetP Hx; apply: mulG_subr. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgr_id
remgrMidx y : x \in K -> y \in H -> remgr K H (x * y) = y. Proof. by move=> Kx Hy; rewrite remgrMl ?remgr_id. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgrMid
divgrMidx y : x \in K -> y \in H -> divgr K H (x * y) = x. Proof. by move=> Kx Hy; rewrite /divgr remgrMid ?mulgK. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgrMid
subcent_TImulgK H A : K :&: H = 1 -> A \subset 'N(K) :&: 'N(H) -> 'C_K(A) * 'C_H(A) = 'C_(K * H)(A). Proof. move=> tiKH /subsetIP[nKA nHA]; apply/eqP. rewrite group_modl ?subsetIr // eqEsubset setSI ?mulSg ?subsetIl //=. apply/subsetP=> _ /setIP[/mulsgP[x y Kx Hy ->] cAxy]. rewrite inE cAxy mem_mulg // inE Kx /=. apply/centP=> z Az; apply/commgP/conjg_fixP. move/commgP/conjg_fixP/(congr1 (divgr K H)): (centP cAxy z Az). by rewrite conjMg !divgrMid ?memJ_norm // (subsetP nKA, subsetP nHA). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
subcent_TImulg
complPH A B : reflect (A :&: H = 1 /\ A * H = B) (H \in [complements to A in B]). Proof. by apply: (iffP setIdP); case; split; apply/eqP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
complP
splitsPB A : reflect (exists H, H \in [complements to A in B]) [splits B, over A]. Proof. exact: set0Pn. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
splitsP
complgCH K G : (H \in [complements to K in G]) = (K \in [complements to H in G]). Proof. rewrite !inE setIC; congr (_ && _). by apply/eqP/eqP=> defG; rewrite -(comm_group_setP _) // defG groupP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
complgC
remgrM: K <| G -> {in G &, {morph remgr K H : x y / x * y}}. Proof. case/normalP=> _; case/complP: complH_K => tiKH <- nK_KH x y KHx KHy. rewrite {1}(divgr_eq K H y) mulgA (conjgCV x) {2}(divgr_eq K H x) -mulgA. rewrite -[X in _ * X]mulgA mulgA remgrMid //; last first. by rewrite groupMl mem_remgr. by rewrite groupMl !(=^~ mem_conjg, nK_KH, mem_divgr). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
remgrM
divgrM: H \subset 'C(K) -> {in G &, {morph divgr K H : x y / x * y}}. Proof. move=> cKH; have /complP[_ defG] := complH_K. have nsKG: K <| G by rewrite -defG -cent_joinEr // normalYl cents_norm. move=> x y Gx Gy; rewrite {1}/divgr remgrM // invMg -!mulgA (mulgA y). by congr (_ * _); rewrite -(centsP cKH) ?groupV ?(mem_remgr, mem_divgr, defG). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
divgrM
sdprod1g: left_id 1 sdprod. Proof. by move=> A; rewrite /sdprod subsetIl pprod1g. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod1g
sdprodg1: right_id 1 sdprod. Proof. by move=> A; rewrite /sdprod subsetIr pprodg1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodg1
sdprodPA B G : A ><| B = G -> [/\ are_groups A B, A * B = G, B \subset 'N(A) & A :&: B = 1]. Proof. rewrite /sdprod; case: ifP => [trAB | _ /group_not0[] //]. case/pprodP=> gAB defG nBA; split=> {defG nBA}//. by case: gAB trAB => H K -> -> /trivgP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodP
sdprodEK H : H \subset 'N(K) -> K :&: H = 1 -> K ><| H = K * H. Proof. by move=> nKH tiKH; rewrite /sdprod tiKH subxx pprodE. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodE
sdprodEYK H : H \subset 'N(K) -> K :&: H = 1 -> K ><| H = K <*> H. Proof. by move=> nKH tiKH; rewrite sdprodE ?norm_joinEr. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodEY
sdprodWppA B G : A ><| B = G -> pprod A B = G. Proof. by case/sdprodP=> [[K H -> ->] <- /pprodE]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodWpp
sdprodWA B G : A ><| B = G -> A * B = G. Proof. by move/sdprodWpp/pprodW. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodW
sdprodWCA B G : A ><| B = G -> B * A = G. Proof. by move/sdprodWpp/pprodWC. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodWC
sdprodWYA B G : A ><| B = G -> A <*> B = G. Proof. by move/sdprodWpp/pprodWY. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodWY
sdprodJA B x : (A ><| B) :^ x = A :^ x ><| B :^ x. Proof. rewrite /sdprod -conjIg sub_conjg conjs1g -pprodJ. by case: ifP => _ //; apply: imset0. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprodJ
sdprod_contextG K H : K ><| H = G -> [/\ K <| G, H \subset G, K * H = G, H \subset 'N(K) & K :&: H = 1]. Proof. case/sdprodP=> _ <- nKH tiKH. by rewrite /normal mulG_subl mulG_subr mulG_subG normG. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_context
sdprod_complG K H : K ><| H = G -> H \in [complements to K in G]. Proof. by case/sdprodP=> _ mulKH _ tiKH; apply/complP. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_compl
sdprod_normal_complPG K H : K <| G -> reflect (K ><| H = G) (K \in [complements to H in G]). Proof. case/andP=> _ nKG; rewrite complgC. apply: (iffP idP); [case/complP=> tiKH mulKH | exact: sdprod_compl]. by rewrite sdprodE ?(subset_trans _ nKG) // -mulKH mulG_subr. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_normal_complP
sdprod_cardG A B : A ><| B = G -> (#|A| * #|B|)%N = #|G|. Proof. by case/sdprodP=> [[H K -> ->] <- _ /TI_cardMg]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_card
sdprod_isomG A B : A ><| B = G -> {nAB : B \subset 'N(A) | isom B (G / A) (restrm nAB (coset A))}. Proof. case/sdprodP=> [[K H -> ->] <- nKH tiKH]. by exists nKH; rewrite quotientMidl quotient_isom. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_isom
sdprod_isogG A B : A ><| B = G -> B \isog G / A. Proof. by case/sdprod_isom=> nAB; apply: isom_isog. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_isog
sdprod_subrG A B M : A ><| B = G -> M \subset B -> A ><| M = A <*> M. Proof. case/sdprodP=> [[K H -> ->] _ nKH tiKH] sMH. by rewrite sdprodEY ?(subset_trans sMH) //; apply/trivgP; rewrite -tiKH setIS. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_subr
index_sdprodG A B : A ><| B = G -> #|B| = #|G : A|. Proof. case/sdprodP=> [[K H -> ->] <- _ tiHK]. by rewrite indexMg -indexgI setIC tiHK indexg1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
index_sdprod
index_sdprodrG A B M : A ><| B = G -> M \subset B -> #|B : M| = #|G : A <*> M|. Proof. move=> defG; case/sdprodP: defG (defG) => [[K H -> ->] mulKH nKH _] defG sMH. rewrite -!divgS //=; last by rewrite -genM_join gen_subG -mulKH mulgS. by rewrite -(sdprod_card defG) -(sdprod_card (sdprod_subr defG sMH)) divnMl. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
index_sdprodr
quotient_sdprodr_isomG A B M : A ><| B = G -> M <| B -> {f : {morphism B / M >-> coset_of (A <*> M)} | isom (B / M) (G / (A <*> M)) f & forall L, L \subset B -> f @* (L / M) = A <*> L / (A <*> M)}. Proof. move=> defG nsMH; have [defA defB]: A = <<A>>%G /\ B = <<B>>%G. by have [[K1 H1 -> ->] _ _ _] := sdprodP defG; rewrite /= !genGid. do [rewrite {}defA {}defB; move: {A}<<A>>%G {B}<<B>>%G => K H] in defG nsMH *. have [[nKH /isomP[injKH imKH]] sMH] := (sdprod_isom defG, normal_sub nsMH). have [[nsKG sHG mulKH _ _] nKM] := (sdprod_context defG, subset_trans sMH nKH). have nsKMG: K <*> M <| G. by rewrite -quotientYK // -mulKH -quotientK ?cosetpre_normal ?quotient_normal. have [/= f inj_f im_f] := third_isom (joing_subl K M) nsKG nsKMG. rewrite quotientYidl //= -imKH -(restrm_quotientE nKH sMH) in f inj_f im_f. have /domP[h [_ ker_h _ im_h]]: 'dom (f \o quotm _ nsMH) = H / M. by rewrite ['dom _]morphpre_quotm injmK. have{} im_h L: L \subset H -> h @* (L / M) = K <*> L / (K <*> M). move=> sLH; have [sLG sKKM] := (subset_trans sLH sHG, joing_subl K M). rewrite im_h morphim_comp morphim_quotm [_ @* L]restrm_quotientE ?im_f //. rewrite quotientY ?(normsG sKKM) ?(subset_trans sLG) ?normal_norm //. by rewrite (quotientS1 sKKM) joing1G. exists h => //; apply/isomP; split; last by rewrite im_h //= (sdprodWY defG). by rewrite ker_h injm_comp ?injm_quotm. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
quotient_sdprodr_isom
quotient_sdprodr_isogG A B M : A ><| B = G -> M <| B -> B / M \isog G / (A <*> M). Proof. move=> defG; case/sdprodP: defG (defG) => [[K H -> ->] _ _ _] => defG nsMH. by have [h /isom_isog->] := quotient_sdprodr_isom defG nsMH. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
quotient_sdprodr_isog
sdprod_modlA B G H : A ><| B = G -> A \subset H -> A ><| (B :&: H) = G :&: H. Proof. case/sdprodP=> {A B} [[A B -> ->]] <- nAB tiAB sAH. rewrite -group_modl ?sdprodE ?subIset ?nAB //. by rewrite setIA tiAB (setIidPl _) ?sub1G. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_modl
sdprod_modrA B G H : A ><| B = G -> B \subset H -> (H :&: A) ><| B = H :&: G. Proof. case/sdprodP=> {A B}[[A B -> ->]] <- nAB tiAB sAH. rewrite -group_modr ?sdprodE ?normsI // ?normsG //. by rewrite -setIA tiAB (setIidPr _) ?sub1G. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_modr
subcent_sdprodB C G A : B ><| C = G -> A \subset 'N(B) :&: 'N(C) -> 'C_B(A) ><| 'C_C(A) = 'C_G(A). Proof. case/sdprodP=> [[H K -> ->] <- nHK tiHK] nHKA {B C G}. rewrite sdprodE ?subcent_TImulg ?normsIG //. by rewrite -setIIl tiHK (setIidPl (sub1G _)). Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
subcent_sdprod
sdprod_recln G K H K1 : #|G| <= n -> K ><| H = G -> K1 \proper K -> H \subset 'N(K1) -> exists G1 : {group gT}, [/\ #|G1| < n, G1 \subset G & K1 ><| H = G1]. Proof. move=> leGn; case/sdprodP=> _ defG nKH tiKH ltK1K nK1H. have tiK1H: K1 :&: H = 1 by apply/trivgP; rewrite -tiKH setSI ?proper_sub. exists (K1 <*> H)%G; rewrite /= -defG sdprodE // norm_joinEr //. rewrite ?mulSg ?proper_sub ?(leq_trans _ leGn) //=. by rewrite -defG ?TI_cardMg // ltn_pmul2r ?proper_card. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_recl
sdprod_recrn G K H H1 : #|G| <= n -> K ><| H = G -> H1 \proper H -> exists G1 : {group gT}, [/\ #|G1| < n, G1 \subset G & K ><| H1 = G1]. Proof. move=> leGn; case/sdprodP=> _ defG nKH tiKH ltH1H. have [sH1H _] := andP ltH1H; have nKH1 := subset_trans sH1H nKH. have tiKH1: K :&: H1 = 1 by apply/trivgP; rewrite -tiKH setIS. exists (K <*> H1)%G; rewrite /= -defG sdprodE // norm_joinEr //. rewrite ?mulgS // ?(leq_trans _ leGn) //=. by rewrite -defG ?TI_cardMg // ltn_pmul2l ?proper_card. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
sdprod_recr
mem_sdprodG A B x : A ><| B = G -> x \in G -> exists y, exists z, [/\ y \in A, z \in B, x = y * z & {in A & B, forall u t, x = u * t -> u = y /\ t = z}]. Proof. case/sdprodP=> [[K H -> ->{A B}] <- _ tiKH] /mulsgP[y z Ky Hz ->{x}]. exists y; exists z; split=> // u t Ku Ht eqyzut. move: (congr1 (divgr K H) eqyzut) (congr1 (remgr K H) eqyzut). by rewrite !remgrMid // !divgrMid. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
mem_sdprod
cprod1g: left_id 1 cprod. Proof. by move=> A; rewrite /cprod cents1 pprod1g. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprod1g
cprodg1: right_id 1 cprod. Proof. by move=> A; rewrite /cprod sub1G pprodg1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodg1
cprodPA B G : A \* B = G -> [/\ are_groups A B, A * B = G & B \subset 'C(A)]. Proof. by rewrite /cprod; case: ifP => [cAB /pprodP[] | _ /group_not0[]]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodP
cprodEG H : H \subset 'C(G) -> G \* H = G * H. Proof. by move=> cGH; rewrite /cprod cGH pprodE ?cents_norm. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodE
cprodEYG H : H \subset 'C(G) -> G \* H = G <*> H. Proof. by move=> cGH; rewrite cprodE ?cent_joinEr. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodEY
cprodWppA B G : A \* B = G -> pprod A B = G. Proof. by case/cprodP=> [[K H -> ->] <- /cents_norm/pprodE]. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodWpp
cprodWA B G : A \* B = G -> A * B = G. Proof. by move/cprodWpp/pprodW. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodW
cprodWCA B G : A \* B = G -> B * A = G. Proof. by move/cprodWpp/pprodWC. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodWC
cprodWYA B G : A \* B = G -> A <*> B = G. Proof. by move/cprodWpp/pprodWY. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodWY
cprodJA B x : (A \* B) :^ x = A :^ x \* B :^ x. Proof. by rewrite /cprod centJ conjSg -pprodJ; case: ifP => _ //; apply: imset0. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprodJ
cprod_normal2A B G : A \* B = G -> A <| G /\ B <| G. Proof. case/cprodP=> [[K H -> ->] <- cKH]; rewrite -cent_joinEr //. by rewrite normalYl normalYr !cents_norm // centsC. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprod_normal2
bigcprodWI (r : seq I) P F G : \big[cprod/1]_(i <- r | P i) F i = G -> \prod_(i <- r | P i) F i = G. Proof. elim/big_rec2: _ G => // i A B _ IH G /cprodP[[_ H _ defB] <- _]. by rewrite (IH H) defB. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
bigcprodW
bigcprodWYI (r : seq I) P F G : \big[cprod/1]_(i <- r | P i) F i = G -> << \bigcup_(i <- r | P i) F i >> = G. Proof. elim/big_rec2: _ G => [|i A B _ IH G]; first by rewrite gen0. case/cprodP => [[K H -> defB] <- cKH]. by rewrite -[<<_>>]joing_idr (IH H) ?cent_joinEr -?defB. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
bigcprodWY
triv_cprodA B : (A \* B == 1) = (A == 1) && (B == 1). Proof. case A1: (A == 1); first by rewrite (eqP A1) cprod1g. apply/eqP=> /cprodP[[G H defA ->]] /eqP. by rewrite defA trivMg -defA A1. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
triv_cprod
cprod_ntrivA B : A != 1 -> B != 1 -> A \* B = if [&& group_set A, group_set B & B \subset 'C(A)] then A * B else set0. Proof. move=> A1 B1; rewrite /cprod; case: ifP => cAB; rewrite ?cAB ?andbF //=. by rewrite /pprod -if_neg A1 -if_neg B1 cents_norm. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprod_ntriv
trivg0: (@set0 gT == 1) = false. Proof. by rewrite eqEcard cards0 cards1 andbF. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
trivg0
group0: group_set (@set0 gT) = false. Proof. by rewrite /group_set inE. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
group0
cprod0gA : set0 \* A = set0. Proof. by rewrite /cprod centsC sub0set /pprod group0 trivg0 !if_same. Qed.
Lemma
fingroup
[ "From HB Require Import structures", "From mathcomp Require Import ssreflect ssrbool ssrfun eqtype ssrnat seq div", "From mathcomp Require Import choice fintype bigop finset fingroup morphism", "From mathcomp Require Import quotient action finfun" ]
fingroup/gproduct.v
cprod0g