P. 131 of Theorem List - Intuitionistic Logic Explorer

Theorem List for Intuitionistic Logic Explorer - 13001-13100   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	mulgnnsubcl 13001*	Closure of the group multiple (exponentiation) operation in a subsemigroup. (Contributed by Mario Carneiro, 10-Jan-2015.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   &    |- ( ph -> G e. V )   &    |- ( ph -> S C_ B )   &    |- ( ( ph /\ x e. S /\ y e. S ) -> ( x .+ y ) e. S )   =>    |- ( ( ph /\ N e. NN /\ X e. S ) -> ( N .x. X ) e. S )
Theorem	mulgnn0subcl 13002*	Closure of the group multiple (exponentiation) operation in a submonoid. (Contributed by Mario Carneiro, 10-Jan-2015.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   &    |- ( ph -> G e. V )   &    |- ( ph -> S C_ B )   &    |- ( ( ph /\ x e. S /\ y e. S ) -> ( x .+ y ) e. S )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> .0. e. S )   =>    |- ( ( ph /\ N e. NN0 /\ X e. S ) -> ( N .x. X ) e. S )
Theorem	mulgsubcl 13003*	Closure of the group multiple (exponentiation) operation in a subgroup. (Contributed by Mario Carneiro, 10-Jan-2015.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   &    |- ( ph -> G e. V )   &    |- ( ph -> S C_ B )   &    |- ( ( ph /\ x e. S /\ y e. S ) -> ( x .+ y ) e. S )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> .0. e. S )   &    |- I = ( invg ` G )   &    |- ( ( ph /\ x e. S ) -> ( I ` x ) e. S )   =>    |- ( ( ph /\ N e. ZZ /\ X e. S ) -> ( N .x. X ) e. S )
Theorem	mulgnncl 13004	Closure of the group multiple (exponentiation) operation for a positive multiplier in a magma. (Contributed by Mario Carneiro, 11-Dec-2014.) (Revised by AV, 29-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Mgm /\ N e. NN /\ X e. B ) -> ( N .x. X ) e. B )
Theorem	mulgnn0cl 13005	Closure of the group multiple (exponentiation) operation for a nonnegative multiplier in a monoid. (Contributed by Mario Carneiro, 11-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Mnd /\ N e. NN0 /\ X e. B ) -> ( N .x. X ) e. B )
Theorem	mulgcl 13006	Closure of the group multiple (exponentiation) operation. (Contributed by Mario Carneiro, 11-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( N .x. X ) e. B )
Theorem	mulgneg 13007	Group multiple (exponentiation) operation at a negative integer. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by Mario Carneiro, 11-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( -u N .x. X ) = ( I ` ( N .x. X ) ) )
Theorem	mulgnegneg 13008	The inverse of a negative group multiple is the positive group multiple. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 30-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( I ` ( -u N .x. X ) ) = ( N .x. X ) )
Theorem	mulgm1 13009	Group multiple (exponentiation) operation at negative one. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by Mario Carneiro, 20-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ X e. B ) -> ( -u 1 .x. X ) = ( I ` X ) )
Theorem	mulgnn0cld 13010	Closure of the group multiple (exponentiation) operation for a nonnegative multiplier in a monoid. Deduction associated with mulgnn0cl 13005. (Contributed by SN, 1-Feb-2025.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- ( ph -> G e. Mnd )   &    |- ( ph -> N e. NN0 )   &    |- ( ph -> X e. B )   =>    |- ( ph -> ( N .x. X ) e. B )
Theorem	mulgcld 13011	Deduction associated with mulgcl 13006. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> N e. ZZ )   &    |- ( ph -> X e. B )   =>    |- ( ph -> ( N .x. X ) e. B )
Theorem	mulgaddcomlem 13012	Lemma for mulgaddcom 13013. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 31-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( ( G e. Grp /\ y e. ZZ /\ X e. B ) /\ ( ( y .x. X ) .+ X ) = ( X .+ ( y .x. X ) ) ) -> ( ( -u y .x. X ) .+ X ) = ( X .+ ( -u y .x. X ) ) )
Theorem	mulgaddcom 13013	The group multiple operator commutes with the group operation. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 31-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( ( N .x. X ) .+ X ) = ( X .+ ( N .x. X ) ) )
Theorem	mulginvcom 13014	The group multiple operator commutes with the group inverse function. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 31-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( N .x. ( I ` X ) ) = ( I ` ( N .x. X ) ) )
Theorem	mulginvinv 13015	The group multiple operator commutes with the group inverse function. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 31-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( I ` ( N .x. ( I ` X ) ) ) = ( N .x. X ) )
Theorem	mulgnn0z 13016	A group multiple of the identity, for nonnegative multiple. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .0. = ( 0g ` G )   =>    |- ( ( G e. Mnd /\ N e. NN0 ) -> ( N .x. .0. ) = .0. )
Theorem	mulgz 13017	A group multiple of the identity, for integer multiple. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .0. = ( 0g ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ ) -> ( N .x. .0. ) = .0. )
Theorem	mulgnndir 13018	Sum of group multiples, for positive multiples. (Contributed by Mario Carneiro, 11-Dec-2014.) (Revised by AV, 29-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Smgrp /\ ( M e. NN /\ N e. NN /\ X e. B ) ) -> ( ( M + N ) .x. X ) = ( ( M .x. X ) .+ ( N .x. X ) ) )
Theorem	mulgnn0dir 13019	Sum of group multiples, generalized to NN0. (Contributed by Mario Carneiro, 11-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Mnd /\ ( M e. NN0 /\ N e. NN0 /\ X e. B ) ) -> ( ( M + N ) .x. X ) = ( ( M .x. X ) .+ ( N .x. X ) ) )
Theorem	mulgdirlem 13020	Lemma for mulgdir 13021. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Grp /\ ( M e. ZZ /\ N e. ZZ /\ X e. B ) /\ ( M + N ) e. NN0 ) -> ( ( M + N ) .x. X ) = ( ( M .x. X ) .+ ( N .x. X ) ) )
Theorem	mulgdir 13021	Sum of group multiples, generalized to ZZ. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Grp /\ ( M e. ZZ /\ N e. ZZ /\ X e. B ) ) -> ( ( M + N ) .x. X ) = ( ( M .x. X ) .+ ( N .x. X ) ) )
Theorem	mulgp1 13022	Group multiple (exponentiation) operation at a successor, extended to ZZ. (Contributed by Mario Carneiro, 11-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( ( N + 1 ) .x. X ) = ( ( N .x. X ) .+ X ) )
Theorem	mulgneg2 13023	Group multiple (exponentiation) operation at a negative integer. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- I = ( invg ` G )   =>    |- ( ( G e. Grp /\ N e. ZZ /\ X e. B ) -> ( -u N .x. X ) = ( N .x. ( I ` X ) ) )
Theorem	mulgnnass 13024	Product of group multiples, for positive multiples in a semigroup. (Contributed by Mario Carneiro, 13-Dec-2014.) (Revised by AV, 29-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Smgrp /\ ( M e. NN /\ N e. NN /\ X e. B ) ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) )
Theorem	mulgnn0ass 13025	Product of group multiples, generalized to NN0. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Mnd /\ ( M e. NN0 /\ N e. NN0 /\ X e. B ) ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) )
Theorem	mulgass 13026	Product of group multiples, generalized to ZZ. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Grp /\ ( M e. ZZ /\ N e. ZZ /\ X e. B ) ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) )
Theorem	mulgassr 13027	Reversed product of group multiples. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 30-Aug-2021.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Grp /\ ( M e. ZZ /\ N e. ZZ /\ X e. B ) ) -> ( ( N x. M ) .x. X ) = ( M .x. ( N .x. X ) ) )
Theorem	mulgmodid 13028	Casting out multiples of the identity element leaves the group multiple unchanged. (Contributed by Paul Chapman, 17-Apr-2009.) (Revised by AV, 30-Aug-2021.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- .x. = (.g ` G )   =>    |- ( ( G e. Grp /\ ( N e. ZZ /\ M e. NN ) /\ ( X e. B /\ ( M .x. X ) = .0. ) ) -> ( ( N mod M ) .x. X ) = ( N .x. X ) )
Theorem	mulgsubdir 13029	Distribution of group multiples over subtraction for group elements, subdir 8346 analog. (Contributed by Mario Carneiro, 13-Dec-2014.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .- = ( -g ` G )   =>    |- ( ( G e. Grp /\ ( M e. ZZ /\ N e. ZZ /\ X e. B ) ) -> ( ( M - N ) .x. X ) = ( ( M .x. X ) .- ( N .x. X ) ) )
Theorem	mhmmulg 13030	A homomorphism of monoids preserves group multiples. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- B = ( Base ` G )   &    |- .x. = (.g ` G )   &    |- .X. = (.g ` H )   =>    |- ( ( F e. ( G MndHom H ) /\ N e. NN0 /\ X e. B ) -> ( F ` ( N .x. X ) ) = ( N .X. ( F ` X ) ) )
Theorem	mulgpropdg 13031*	Two structures with the same group-nature have the same group multiple function. K is expected to either be _V (when strong equality is available) or B (when closure is available). (Contributed by Stefan O'Rear, 21-Mar-2015.) (Revised by Mario Carneiro, 2-Oct-2015.)
|- ( ph -> .x. = (.g ` G ) )   &    |- ( ph -> .X. = (.g ` H ) )   &    |- ( ph -> G e. V )   &    |- ( ph -> H e. W )   &    |- ( ph -> B = ( Base ` G ) )   &    |- ( ph -> B = ( Base ` H ) )   &    |- ( ph -> B C_ K )   &    |- ( ( ph /\ ( x e. K /\ y e. K ) ) -> ( x ( +g ` G ) y ) e. K )   &    |- ( ( ph /\ ( x e. K /\ y e. K ) ) -> ( x ( +g ` G ) y ) = ( x ( +g ` H ) y ) )   =>    |- ( ph -> .x. = .X. )
Theorem	submmulgcl 13032	Closure of the group multiple (exponentiation) operation in a submonoid. (Contributed by Mario Carneiro, 13-Jan-2015.)
|- .xb = (.g ` G )   =>    |- ( ( S e. (SubMnd ` G ) /\ N e. NN0 /\ X e. S ) -> ( N .xb X ) e. S )
7.2.3  Subgroups and Quotient groups
Syntax	csubg 13033	Extend class notation with all subgroups of a group.
class SubGrp
Syntax	cnsg 13034	Extend class notation with all normal subgroups of a group.
class NrmSGrp
Syntax	cqg 13035	Quotient group equivalence class.
class ~QG
Definition	df-subg 13036*	Define a subgroup of a group as a set of elements that is a group in its own right. Equivalently (issubg2m 13055), a subgroup is a subset of the group that is closed for the group internal operation (see subgcl 13050), contains the neutral element of the group (see subg0 13046) and contains the inverses for all of its elements (see subginvcl 13049). (Contributed by Mario Carneiro, 2-Dec-2014.)
|- SubGrp = ( w e. Grp |-> { s e. ~P ( Base ` w ) | ( w ↾s s ) e. Grp } )
Definition	df-nsg 13037*	Define the equivalence relation in a quotient ring or quotient group (where i is a two-sided ideal or a normal subgroup). For non-normal subgroups this generates the left cosets. (Contributed by Mario Carneiro, 15-Jun-2015.)
|- NrmSGrp = ( w e. Grp |-> { s e. (SubGrp ` w ) | [. ( Base ` w ) / b ]. [. ( +g ` w ) / p ]. A. x e. b A. y e. b ( ( x p y ) e. s <-> ( y p x ) e. s ) } )
Definition	df-eqg 13038*	Define the equivalence relation in a group generated by a subgroup. More precisely, if G is a group and H is a subgroup, then G ~QG H is the equivalence relation on G associated with the left cosets of H. A typical application of this definition is the construction of the quotient group (resp. ring) of a group (resp. ring) by a normal subgroup (resp. two-sided ideal). (Contributed by Mario Carneiro, 15-Jun-2015.)
|- ~QG = ( r e. _V , i e. _V |-> { <. x , y >. | ( { x , y } C_ ( Base ` r ) /\ ( ( ( invg ` r ) ` x ) ( +g ` r ) y ) e. i ) } )
Theorem	issubg 13039	The subgroup predicate. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- B = ( Base ` G )   =>    |- ( S e. (SubGrp ` G ) <-> ( G e. Grp /\ S C_ B /\ ( G ↾s S ) e. Grp ) )
Theorem	subgss 13040	A subgroup is a subset. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- B = ( Base ` G )   =>    |- ( S e. (SubGrp ` G ) -> S C_ B )
Theorem	subgid 13041	A group is a subgroup of itself. (Contributed by Mario Carneiro, 7-Dec-2014.)
|- B = ( Base ` G )   =>    |- ( G e. Grp -> B e. (SubGrp ` G ) )
Theorem	subgex 13042	The class of subgroups of a group is a set. (Contributed by Jim Kingdon, 8-Mar-2025.)
|- ( G e. Grp -> (SubGrp ` G ) e. _V )
Theorem	subggrp 13043	A subgroup is a group. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- H = ( G ↾s S )   =>    |- ( S e. (SubGrp ` G ) -> H e. Grp )
Theorem	subgbas 13044	The base of the restricted group in a subgroup. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- H = ( G ↾s S )   =>    |- ( S e. (SubGrp ` G ) -> S = ( Base ` H ) )
Theorem	subgrcl 13045	Reverse closure for the subgroup predicate. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- ( S e. (SubGrp ` G ) -> G e. Grp )
Theorem	subg0 13046	A subgroup of a group must have the same identity as the group. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 30-Apr-2015.)
|- H = ( G ↾s S )   &    |- .0. = ( 0g ` G )   =>    |- ( S e. (SubGrp ` G ) -> .0. = ( 0g ` H ) )
Theorem	subginv 13047	The inverse of an element in a subgroup is the same as the inverse in the larger group. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- H = ( G ↾s S )   &    |- I = ( invg ` G )   &    |- J = ( invg ` H )   =>    |- ( ( S e. (SubGrp ` G ) /\ X e. S ) -> ( I ` X ) = ( J ` X ) )
Theorem	subg0cl 13048	The group identity is an element of any subgroup. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- .0. = ( 0g ` G )   =>    |- ( S e. (SubGrp ` G ) -> .0. e. S )
Theorem	subginvcl 13049	The inverse of an element is closed in a subgroup. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- I = ( invg ` G )   =>    |- ( ( S e. (SubGrp ` G ) /\ X e. S ) -> ( I ` X ) e. S )
Theorem	subgcl 13050	A subgroup is closed under group operation. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- .+ = ( +g ` G )   =>    |- ( ( S e. (SubGrp ` G ) /\ X e. S /\ Y e. S ) -> ( X .+ Y ) e. S )
Theorem	subgsubcl 13051	A subgroup is closed under group subtraction. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- .- = ( -g ` G )   =>    |- ( ( S e. (SubGrp ` G ) /\ X e. S /\ Y e. S ) -> ( X .- Y ) e. S )
Theorem	subgsub 13052	The subtraction of elements in a subgroup is the same as subtraction in the group. (Contributed by Mario Carneiro, 15-Jun-2015.)
|- .- = ( -g ` G )   &    |- H = ( G ↾s S )   &    |- N = ( -g ` H )   =>    |- ( ( S e. (SubGrp ` G ) /\ X e. S /\ Y e. S ) -> ( X .- Y ) = ( X N Y ) )
Theorem	subgmulgcl 13053	Closure of the group multiple (exponentiation) operation in a subgroup. (Contributed by Mario Carneiro, 13-Jan-2015.)
|- .x. = (.g ` G )   =>    |- ( ( S e. (SubGrp ` G ) /\ N e. ZZ /\ X e. S ) -> ( N .x. X ) e. S )
Theorem	subgmulg 13054	A group multiple is the same if evaluated in a subgroup. (Contributed by Mario Carneiro, 15-Jan-2015.)
|- .x. = (.g ` G )   &    |- H = ( G ↾s S )   &    |- .xb = (.g ` H )   =>    |- ( ( S e. (SubGrp ` G ) /\ N e. ZZ /\ X e. S ) -> ( N .x. X ) = ( N .xb X ) )
Theorem	issubg2m 13055*	Characterize the subgroups of a group by closure properties. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- B = ( Base ` G )   &    |- .+ = ( +g ` G )   &    |- I = ( invg ` G )   =>    |- ( G e. Grp -> ( S e. (SubGrp ` G ) <-> ( S C_ B /\ E. u u e. S /\ A. x e. S ( A. y e. S ( x .+ y ) e. S /\ ( I ` x ) e. S ) ) ) )
Theorem	issubgrpd2 13056*	Prove a subgroup by closure (definition version). (Contributed by Stefan O'Rear, 7-Dec-2014.)
|- ( ph -> S = ( I ↾s D ) )   &    |- ( ph -> .0. = ( 0g ` I ) )   &    |- ( ph -> .+ = ( +g ` I ) )   &    |- ( ph -> D C_ ( Base ` I ) )   &    |- ( ph -> .0. e. D )   &    |- ( ( ph /\ x e. D /\ y e. D ) -> ( x .+ y ) e. D )   &    |- ( ( ph /\ x e. D ) -> ( ( invg ` I ) ` x ) e. D )   &    |- ( ph -> I e. Grp )   =>    |- ( ph -> D e. (SubGrp ` I ) )
Theorem	issubgrpd 13057*	Prove a subgroup by closure. (Contributed by Stefan O'Rear, 7-Dec-2014.)
|- ( ph -> S = ( I ↾s D ) )   &    |- ( ph -> .0. = ( 0g ` I ) )   &    |- ( ph -> .+ = ( +g ` I ) )   &    |- ( ph -> D C_ ( Base ` I ) )   &    |- ( ph -> .0. e. D )   &    |- ( ( ph /\ x e. D /\ y e. D ) -> ( x .+ y ) e. D )   &    |- ( ( ph /\ x e. D ) -> ( ( invg ` I ) ` x ) e. D )   &    |- ( ph -> I e. Grp )   =>    |- ( ph -> S e. Grp )
Theorem	issubg3 13058*	A subgroup is a symmetric submonoid. (Contributed by Mario Carneiro, 7-Mar-2015.)
|- I = ( invg ` G )   =>    |- ( G e. Grp -> ( S e. (SubGrp ` G ) <-> ( S e. (SubMnd ` G ) /\ A. x e. S ( I ` x ) e. S ) ) )
Theorem	issubg4m 13059*	A subgroup is an inhabited subset of the group closed under subtraction. (Contributed by Mario Carneiro, 17-Sep-2015.)
|- B = ( Base ` G )   &    |- .- = ( -g ` G )   =>    |- ( G e. Grp -> ( S e. (SubGrp ` G ) <-> ( S C_ B /\ E. w w e. S /\ A. x e. S A. y e. S ( x .- y ) e. S ) ) )
Theorem	grpissubg 13060	If the base set of a group is contained in the base set of another group, and the group operation of the group is the restriction of the group operation of the other group to its base set, then the (base set of the) group is subgroup of the other group. (Contributed by AV, 14-Mar-2019.)
|- B = ( Base ` G )   &    |- S = ( Base ` H )   =>    |- ( ( G e. Grp /\ H e. Grp ) -> ( ( S C_ B /\ ( +g ` H ) = ( ( +g ` G ) |` ( S X. S ) ) ) -> S e. (SubGrp ` G ) ) )
Theorem	resgrpisgrp 13061	If the base set of a group is contained in the base set of another group, and the group operation of the group is the restriction of the group operation of the other group to its base set, then the other group restricted to the base set of the group is a group. (Contributed by AV, 14-Mar-2019.)
|- B = ( Base ` G )   &    |- S = ( Base ` H )   =>    |- ( ( G e. Grp /\ H e. Grp ) -> ( ( S C_ B /\ ( +g ` H ) = ( ( +g ` G ) |` ( S X. S ) ) ) -> ( G ↾s S ) e. Grp ) )
Theorem	subgsubm 13062	A subgroup is a submonoid. (Contributed by Mario Carneiro, 18-Jun-2015.)
|- ( S e. (SubGrp ` G ) -> S e. (SubMnd ` G ) )
Theorem	subsubg 13063	A subgroup of a subgroup is a subgroup. (Contributed by Mario Carneiro, 19-Jan-2015.)
|- H = ( G ↾s S )   =>    |- ( S e. (SubGrp ` G ) -> ( A e. (SubGrp ` H ) <-> ( A e. (SubGrp ` G ) /\ A C_ S ) ) )
Theorem	subgintm 13064*	The intersection of an inhabited collection of subgroups is a subgroup. (Contributed by Mario Carneiro, 7-Dec-2014.)
|- ( ( S C_ (SubGrp ` G ) /\ E. w w e. S ) -> |^| S e. (SubGrp ` G ) )
Theorem	0subg 13065	The zero subgroup of an arbitrary group. (Contributed by Stefan O'Rear, 10-Dec-2014.) (Proof shortened by SN, 31-Jan-2025.)
|- .0. = ( 0g ` G )   =>    |- ( G e. Grp -> { .0. } e. (SubGrp ` G ) )
Theorem	trivsubgd 13066	The only subgroup of a trivial group is itself. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> B = { .0. } )   &    |- ( ph -> A e. (SubGrp ` G ) )   =>    |- ( ph -> A = B )
Theorem	trivsubgsnd 13067	The only subgroup of a trivial group is itself. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> B = { .0. } )   =>    |- ( ph -> (SubGrp ` G ) = { B } )
Theorem	isnsg 13068*	Property of being a normal subgroup. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( S e. (NrmSGrp ` G ) <-> ( S e. (SubGrp ` G ) /\ A. x e. X A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) ) )
Theorem	isnsg2 13069*	Weaken the condition of isnsg 13068 to only one side of the implication. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( S e. (NrmSGrp ` G ) <-> ( S e. (SubGrp ` G ) /\ A. x e. X A. y e. X ( ( x .+ y ) e. S -> ( y .+ x ) e. S ) ) )
Theorem	nsgbi 13070	Defining property of a normal subgroup. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( ( S e. (NrmSGrp ` G ) /\ A e. X /\ B e. X ) -> ( ( A .+ B ) e. S <-> ( B .+ A ) e. S ) )
Theorem	nsgsubg 13071	A normal subgroup is a subgroup. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- ( S e. (NrmSGrp ` G ) -> S e. (SubGrp ` G ) )
Theorem	nsgconj 13072	The conjugation of an element of a normal subgroup is in the subgroup. (Contributed by Mario Carneiro, 4-Feb-2015.)
|- X = ( Base ` G )   &    |- .+ = ( +g ` G )   &    |- .- = ( -g ` G )   =>    |- ( ( S e. (NrmSGrp ` G ) /\ A e. X /\ B e. S ) -> ( ( A .+ B ) .- A ) e. S )
Theorem	isnsg3 13073*	A subgroup is normal iff the conjugation of all the elements of the subgroup is in the subgroup. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- X = ( Base ` G )   &    |- .+ = ( +g ` G )   &    |- .- = ( -g ` G )   =>    |- ( S e. (NrmSGrp ` G ) <-> ( S e. (SubGrp ` G ) /\ A. x e. X A. y e. S ( ( x .+ y ) .- x ) e. S ) )
Theorem	elnmz 13074*	Elementhood in the normalizer. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   =>    |- ( A e. N <-> ( A e. X /\ A. z e. X ( ( A .+ z ) e. S <-> ( z .+ A ) e. S ) ) )
Theorem	nmzbi 13075*	Defining property of the normalizer. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   =>    |- ( ( A e. N /\ B e. X ) -> ( ( A .+ B ) e. S <-> ( B .+ A ) e. S ) )
Theorem	nmzsubg 13076*	The normalizer NG(S) of a subset S of the group is a subgroup. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   &    |- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( G e. Grp -> N e. (SubGrp ` G ) )
Theorem	ssnmz 13077*	A subgroup is a subset of its normalizer. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   &    |- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( S e. (SubGrp ` G ) -> S C_ N )
Theorem	isnsg4 13078*	A subgroup is normal iff its normalizer is the entire group. (Contributed by Mario Carneiro, 18-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   &    |- X = ( Base ` G )   &    |- .+ = ( +g ` G )   =>    |- ( S e. (NrmSGrp ` G ) <-> ( S e. (SubGrp ` G ) /\ N = X ) )
Theorem	nmznsg 13079*	Any subgroup is a normal subgroup of its normalizer. (Contributed by Mario Carneiro, 19-Jan-2015.)
|- N = { x e. X | A. y e. X ( ( x .+ y ) e. S <-> ( y .+ x ) e. S ) }   &    |- X = ( Base ` G )   &    |- .+ = ( +g ` G )   &    |- H = ( G ↾s N )   =>    |- ( S e. (SubGrp ` G ) -> S e. (NrmSGrp ` H ) )
Theorem	0nsg 13080	The zero subgroup is normal. (Contributed by Mario Carneiro, 4-Feb-2015.)
|- .0. = ( 0g ` G )   =>    |- ( G e. Grp -> { .0. } e. (NrmSGrp ` G ) )
Theorem	nsgid 13081	The whole group is a normal subgroup of itself. (Contributed by Mario Carneiro, 4-Feb-2015.)
|- B = ( Base ` G )   =>    |- ( G e. Grp -> B e. (NrmSGrp ` G ) )
Theorem	0idnsgd 13082	The whole group and the zero subgroup are normal subgroups of a group. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   =>    |- ( ph -> { { .0. } , B } C_ (NrmSGrp ` G ) )
Theorem	trivnsgd 13083	The only normal subgroup of a trivial group is itself. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> B = { .0. } )   =>    |- ( ph -> (NrmSGrp ` G ) = { B } )
Theorem	triv1nsgd 13084	A trivial group has exactly one normal subgroup. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> B = { .0. } )   =>    |- ( ph -> (NrmSGrp ` G ) ~~ 1o )
Theorem	1nsgtrivd 13085	A group with exactly one normal subgroup is trivial. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- B = ( Base ` G )   &    |- .0. = ( 0g ` G )   &    |- ( ph -> G e. Grp )   &    |- ( ph -> (NrmSGrp ` G ) ~~ 1o )   =>    |- ( ph -> B = { .0. } )
Theorem	releqgg 13086	The left coset equivalence relation is a relation. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- R = ( G ~QG S )   =>    |- ( ( G e. V /\ S e. W ) -> Rel R )
Theorem	eqgfval 13087*	Value of the subgroup left coset equivalence relation. (Contributed by Mario Carneiro, 15-Jan-2015.)
|- X = ( Base ` G )   &    |- N = ( invg ` G )   &    |- .+ = ( +g ` G )   &    |- R = ( G ~QG S )   =>    |- ( ( G e. V /\ S C_ X ) -> R = { <. x , y >. | ( { x , y } C_ X /\ ( ( N ` x ) .+ y ) e. S ) } )
Theorem	eqgval 13088	Value of the subgroup left coset equivalence relation. (Contributed by Mario Carneiro, 15-Jan-2015.) (Revised by Mario Carneiro, 14-Jun-2015.)
|- X = ( Base ` G )   &    |- N = ( invg ` G )   &    |- .+ = ( +g ` G )   &    |- R = ( G ~QG S )   =>    |- ( ( G e. V /\ S C_ X ) -> ( A R B <-> ( A e. X /\ B e. X /\ ( ( N ` A ) .+ B ) e. S ) ) )
Theorem	eqger 13089	The subgroup coset equivalence relation is an equivalence relation. (Contributed by Mario Carneiro, 13-Jan-2015.)
|- X = ( Base ` G )   &    |- .~ = ( G ~QG Y )   =>    |- ( Y e. (SubGrp ` G ) -> .~ Er X )
Theorem	eqglact 13090*	A left coset can be expressed as the image of a left action. (Contributed by Mario Carneiro, 20-Sep-2015.)
|- X = ( Base ` G )   &    |- .~ = ( G ~QG Y )   &    |- .+ = ( +g ` G )   =>    |- ( ( G e. Grp /\ Y C_ X /\ A e. X ) -> [ A ] .~ = ( ( x e. X |-> ( A .+ x ) ) " Y ) )
Theorem	eqgid 13091	The left coset containing the identity is the original subgroup. (Contributed by Mario Carneiro, 20-Sep-2015.)
|- X = ( Base ` G )   &    |- .~ = ( G ~QG Y )   &    |- .0. = ( 0g ` G )   =>    |- ( Y e. (SubGrp ` G ) -> [ .0. ] .~ = Y )
Theorem	eqgen 13092	Each coset is equipotent to the subgroup itself (which is also the coset containing the identity). (Contributed by Mario Carneiro, 20-Sep-2015.)
|- X = ( Base ` G )   &    |- .~ = ( G ~QG Y )   =>    |- ( ( Y e. (SubGrp ` G ) /\ A e. ( X /. .~ ) ) -> Y ~~ A )
Theorem	eqgcpbl 13093	The subgroup coset equivalence relation is compatible with addition when the subgroup is normal. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- X = ( Base ` G )   &    |- .~ = ( G ~QG Y )   &    |- .+ = ( +g ` G )   =>    |- ( Y e. (NrmSGrp ` G ) -> ( ( A .~ C /\ B .~ D ) -> ( A .+ B ) .~ ( C .+ D ) ) )
7.2.4  Abelian groups
7.2.4.1  Definition and basic properties
Syntax	ccmn 13094	Extend class notation with class of all commutative monoids.
class CMnd
Syntax	cabl 13095	Extend class notation with class of all Abelian groups.
class Abel
Definition	df-cmn 13096*	Define class of all commutative monoids. (Contributed by Mario Carneiro, 6-Jan-2015.)
|- CMnd = { g e. Mnd | A. a e. ( Base ` g ) A. b e. ( Base ` g ) ( a ( +g ` g ) b ) = ( b ( +g ` g ) a ) }
Definition	df-abl 13097	Define class of all Abelian groups. (Contributed by NM, 17-Oct-2011.) (Revised by Mario Carneiro, 6-Jan-2015.)
|- Abel = ( Grp i^i CMnd )
Theorem	isabl 13098	The predicate "is an Abelian (commutative) group". (Contributed by NM, 17-Oct-2011.)
|- ( G e. Abel <-> ( G e. Grp /\ G e. CMnd ) )
Theorem	ablgrp 13099	An Abelian group is a group. (Contributed by NM, 26-Aug-2011.)
|- ( G e. Abel -> G e. Grp )
Theorem	ablgrpd 13100	An Abelian group is a group, deduction form of ablgrp 13099. (Contributed by Rohan Ridenour, 3-Aug-2023.)
|- ( ph -> G e. Abel )   =>    |- ( ph -> G e. Grp )