P. 149 of Theorem List - Intuitionistic Logic Explorer

Theorem List for Intuitionistic Logic Explorer - 14801-14900   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	lspsneli 14801	A scalar product with a vector belongs to the span of its singleton. (Contributed by NM, 2-Jul-2014.)
|- V = ( Base ` W )   &    |- .x. = ( .s ` W )   &    |- F = (Scalar ` W )   &    |- K = ( Base ` F )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> A e. K )   &    |- ( ph -> X e. V )   =>    |- ( ph -> ( A .x. X ) e. ( N ` { X } ) )
Theorem	lspsn 14802*	Span of the singleton of a vector. (Contributed by NM, 14-Jan-2014.) (Proof shortened by Mario Carneiro, 19-Jun-2014.)
|- F = (Scalar ` W )   &    |- K = ( Base ` F )   &    |- V = ( Base ` W )   &    |- .x. = ( .s ` W )   &    |- N = ( LSpan ` W )   =>    |- ( ( W e. LMod /\ X e. V ) -> ( N ` { X } ) = { v | E. k e. K v = ( k .x. X ) } )
Theorem	ellspsn 14803*	Member of span of the singleton of a vector. (Contributed by NM, 22-Feb-2014.) (Revised by Mario Carneiro, 19-Jun-2014.)
|- F = (Scalar ` W )   &    |- K = ( Base ` F )   &    |- V = ( Base ` W )   &    |- .x. = ( .s ` W )   &    |- N = ( LSpan ` W )   =>    |- ( ( W e. LMod /\ X e. V ) -> ( U e. ( N ` { X } ) <-> E. k e. K U = ( k .x. X ) ) )
Theorem	lspsnvsi 14804	Span of a scalar product of a singleton. (Contributed by NM, 23-Apr-2014.) (Proof shortened by Mario Carneiro, 4-Sep-2014.)
|- F = (Scalar ` W )   &    |- K = ( Base ` F )   &    |- V = ( Base ` W )   &    |- .x. = ( .s ` W )   &    |- N = ( LSpan ` W )   =>    |- ( ( W e. LMod /\ R e. K /\ X e. V ) -> ( N ` { ( R .x. X ) } ) C_ ( N ` { X } ) )
Theorem	lspsnss2 14805*	Comparable spans of singletons must have proportional vectors. (Contributed by NM, 7-Jun-2015.)
|- V = ( Base ` W )   &    |- S = (Scalar ` W )   &    |- K = ( Base ` S )   &    |- .x. = ( .s ` W )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> X e. V )   &    |- ( ph -> Y e. V )   =>    |- ( ph -> ( ( N ` { X } ) C_ ( N ` { Y } ) <-> E. k e. K X = ( k .x. Y ) ) )
Theorem	lspsnneg 14806	Negation does not change the span of a singleton. (Contributed by NM, 24-Apr-2014.) (Proof shortened by Mario Carneiro, 19-Jun-2014.)
|- V = ( Base ` W )   &    |- M = ( invg ` W )   &    |- N = ( LSpan ` W )   =>    |- ( ( W e. LMod /\ X e. V ) -> ( N ` { ( M ` X ) } ) = ( N ` { X } ) )
Theorem	lspsnsub 14807	Swapping subtraction order does not change the span of a singleton. (Contributed by NM, 4-Apr-2015.)
|- V = ( Base ` W )   &    |- .- = ( -g ` W )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> X e. V )   &    |- ( ph -> Y e. V )   =>    |- ( ph -> ( N ` { ( X .- Y ) } ) = ( N ` { ( Y .- X ) } ) )
Theorem	lspsn0 14808	Span of the singleton of the zero vector. (Contributed by NM, 15-Jan-2014.) (Proof shortened by Mario Carneiro, 19-Jun-2014.)
|- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   =>    |- ( W e. LMod -> ( N ` { .0. } ) = { .0. } )
Theorem	lsp0 14809	Span of the empty set. (Contributed by Mario Carneiro, 5-Sep-2014.)
|- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   =>    |- ( W e. LMod -> ( N ` (/) ) = { .0. } )
Theorem	lspuni0 14810	Union of the span of the empty set. (Contributed by NM, 14-Mar-2015.)
|- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   =>    |- ( W e. LMod -> U. ( N ` (/) ) = .0. )
Theorem	lspun0 14811	The span of a union with the zero subspace. (Contributed by NM, 22-May-2015.)
|- V = ( Base ` W )   &    |- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> X C_ V )   =>    |- ( ph -> ( N ` ( X u. { .0. } ) ) = ( N ` X ) )
Theorem	lspsneq0 14812	Span of the singleton is the zero subspace iff the vector is zero. (Contributed by NM, 27-Apr-2014.) (Revised by Mario Carneiro, 19-Jun-2014.)
|- V = ( Base ` W )   &    |- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   =>    |- ( ( W e. LMod /\ X e. V ) -> ( ( N ` { X } ) = { .0. } <-> X = .0. ) )
Theorem	lspsneq0b 14813	Equal singleton spans imply both arguments are zero or both are nonzero. (Contributed by NM, 21-Mar-2015.)
|- V = ( Base ` W )   &    |- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> X e. V )   &    |- ( ph -> Y e. V )   &    |- ( ph -> ( N ` { X } ) = ( N ` { Y } ) )   =>    |- ( ph -> ( X = .0. <-> Y = .0. ) )
Theorem	lmodindp1 14814	Two independent (non-colinear) vectors have nonzero sum. (Contributed by NM, 22-Apr-2015.)
|- V = ( Base ` W )   &    |- .+ = ( +g ` W )   &    |- .0. = ( 0g ` W )   &    |- N = ( LSpan ` W )   &    |- ( ph -> W e. LMod )   &    |- ( ph -> X e. V )   &    |- ( ph -> Y e. V )   &    |- ( ph -> ( N ` { X } ) =/= ( N ` { Y } ) )   =>    |- ( ph -> ( X .+ Y ) =/= .0. )
Theorem	lsslsp 14815	Spans in submodules correspond to spans in the containing module. (Contributed by Stefan O'Rear, 12-Dec-2014.) Terms in the equation were swapped as proposed by NM on 15-Mar-2015. (Revised by AV, 18-Apr-2025.)
|- X = ( W ↾s U )   &    |- M = ( LSpan ` W )   &    |- N = ( LSpan ` X )   &    |- L = ( LSubSp ` W )   =>    |- ( ( W e. LMod /\ U e. L /\ G C_ U ) -> ( N ` G ) = ( M ` G ) )
Theorem	lss0v 14816	The zero vector in a submodule equals the zero vector in the including module. (Contributed by NM, 15-Mar-2015.)
|- X = ( W ↾s U )   &    |- .0. = ( 0g ` W )   &    |- Z = ( 0g ` X )   &    |- L = ( LSubSp ` W )   =>    |- ( ( W e. LMod /\ U e. L ) -> Z = .0. )
Theorem	lsspropdg 14817*	If two structures have the same components (properties), they have the same subspace structure. (Contributed by Mario Carneiro, 9-Feb-2015.) (Revised by Mario Carneiro, 14-Jun-2015.)
|- ( ph -> B = ( Base ` K ) )   &    |- ( ph -> B = ( Base ` L ) )   &    |- ( ph -> B C_ W )   &    |- ( ( ph /\ ( x e. W /\ y e. W ) ) -> ( x ( +g ` K ) y ) = ( x ( +g ` L ) y ) )   &    |- ( ( ph /\ ( x e. P /\ y e. B ) ) -> ( x ( .s ` K ) y ) e. W )   &    |- ( ( ph /\ ( x e. P /\ y e. B ) ) -> ( x ( .s ` K ) y ) = ( x ( .s ` L ) y ) )   &    |- ( ph -> P = ( Base ` (Scalar ` K ) ) )   &    |- ( ph -> P = ( Base ` (Scalar ` L ) ) )   &    |- ( ph -> K e. X )   &    |- ( ph -> L e. Y )   =>    |- ( ph -> ( LSubSp ` K ) = ( LSubSp ` L ) )
Theorem	lsppropd 14818*	If two structures have the same components (properties), they have the same span function. (Contributed by Mario Carneiro, 9-Feb-2015.) (Revised by Mario Carneiro, 14-Jun-2015.) (Revised by AV, 24-Apr-2024.)
|- ( ph -> B = ( Base ` K ) )   &    |- ( ph -> B = ( Base ` L ) )   &    |- ( ph -> B C_ W )   &    |- ( ( ph /\ ( x e. W /\ y e. W ) ) -> ( x ( +g ` K ) y ) = ( x ( +g ` L ) y ) )   &    |- ( ( ph /\ ( x e. P /\ y e. B ) ) -> ( x ( .s ` K ) y ) e. W )   &    |- ( ( ph /\ ( x e. P /\ y e. B ) ) -> ( x ( .s ` K ) y ) = ( x ( .s ` L ) y ) )   &    |- ( ph -> P = ( Base ` (Scalar ` K ) ) )   &    |- ( ph -> P = ( Base ` (Scalar ` L ) ) )   &    |- ( ph -> K e. X )   &    |- ( ph -> L e. Y )   =>    |- ( ph -> ( LSpan ` K ) = ( LSpan ` L ) )
7.6  Subring algebras and ideals
7.6.1  Subring algebras
Syntax	csra 14819	Extend class notation with the subring algebra generator.
class subringAlg
Syntax	crglmod 14820	Extend class notation with the left module induced by a ring over itself.
class ringLMod
Definition	df-sra 14821*	Any ring can be regarded as a left algebra over any of its subrings. The function subringAlg associates with any ring and any of its subrings the left algebra consisting in the ring itself regarded as a left algebra over the subring. It has an inner product which is simply the ring product. (Contributed by Mario Carneiro, 27-Nov-2014.) (Revised by Thierry Arnoux, 16-Jun-2019.)
|- subringAlg = ( w e. _V |-> ( s e. ~P ( Base ` w ) |-> ( ( ( w sSet <. (Scalar ` ndx ) , ( w ↾s s ) >. ) sSet <. ( .s ` ndx ) , ( .r ` w ) >. ) sSet <. ( .i ` ndx ) , ( .r ` w ) >. ) ) )
Definition	df-rgmod 14822	Any ring can be regarded as a left algebra over itself. The function ringLMod associates with any ring the left algebra consisting in the ring itself regarded as a left algebra over itself. It has an inner product which is simply the ring product. (Contributed by Stefan O'Rear, 6-Dec-2014.)
|- ringLMod = ( w e. _V |-> ( (subringAlg ` w ) ` ( Base ` w ) ) )
Theorem	sraval 14823	Lemma for srabaseg 14825 through sravscag 14829. (Contributed by Mario Carneiro, 27-Nov-2014.) (Revised by Thierry Arnoux, 16-Jun-2019.)
|- ( ( W e. V /\ S C_ ( Base ` W ) ) -> ( (subringAlg ` W ) ` S ) = ( ( ( W sSet <. (Scalar ` ndx ) , ( W ↾s S ) >. ) sSet <. ( .s ` ndx ) , ( .r ` W ) >. ) sSet <. ( .i ` ndx ) , ( .r ` W ) >. ) )
Theorem	sralemg 14824	Lemma for srabaseg 14825 and similar theorems. (Contributed by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- (Scalar ` ndx ) =/= ( E ` ndx )   &    |- ( .s ` ndx ) =/= ( E ` ndx )   &    |- ( .i ` ndx ) =/= ( E ` ndx )   =>    |- ( ph -> ( E ` W ) = ( E ` A ) )
Theorem	srabaseg 14825	Base set of a subring algebra. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( Base ` W ) = ( Base ` A ) )
Theorem	sraaddgg 14826	Additive operation of a subring algebra. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( +g ` W ) = ( +g ` A ) )
Theorem	sramulrg 14827	Multiplicative operation of a subring algebra. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( .r ` W ) = ( .r ` A ) )
Theorem	srascag 14828	The set of scalars of a subring algebra. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Proof shortened by AV, 12-Nov-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( W ↾s S ) = (Scalar ` A ) )
Theorem	sravscag 14829	The scalar product operation of a subring algebra. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Proof shortened by AV, 12-Nov-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( .r ` W ) = ( .s ` A ) )
Theorem	sraipg 14830	The inner product operation of a subring algebra. (Contributed by Thierry Arnoux, 16-Jun-2019.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( .r ` W ) = ( .i ` A ) )
Theorem	sratsetg 14831	Topology component of a subring algebra. (Contributed by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> (TopSet ` W ) = (TopSet ` A ) )
Theorem	sraex 14832	Existence of a subring algebra. (Contributed by Jim Kingdon, 16-Apr-2025.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> A e. _V )
Theorem	sratopng 14833	Topology component of a subring algebra. (Contributed by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( TopOpen ` W ) = ( TopOpen ` A ) )
Theorem	sradsg 14834	Distance function of a subring algebra. (Contributed by Mario Carneiro, 4-Oct-2015.) (Revised by Thierry Arnoux, 16-Jun-2019.) (Revised by AV, 29-Oct-2024.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> ( dist ` W ) = ( dist ` A ) )
Theorem	sraring 14835	Condition for a subring algebra to be a ring. (Contributed by Thierry Arnoux, 24-Jul-2023.)
|- A = ( (subringAlg ` R ) ` V )   &    |- B = ( Base ` R )   =>    |- ( ( R e. Ring /\ V C_ B ) -> A e. Ring )
Theorem	sralmod 14836	The subring algebra is a left module. (Contributed by Stefan O'Rear, 27-Nov-2014.)
|- A = ( (subringAlg ` W ) ` S )   =>    |- ( S e. (SubRing ` W ) -> A e. LMod )
Theorem	sralmod0g 14837	The subring module inherits a zero from its ring. (Contributed by Stefan O'Rear, 27-Dec-2014.)
|- ( ph -> A = ( (subringAlg ` W ) ` S ) )   &    |- ( ph -> .0. = ( 0g ` W ) )   &    |- ( ph -> S C_ ( Base ` W ) )   &    |- ( ph -> W e. X )   =>    |- ( ph -> .0. = ( 0g ` A ) )
Theorem	issubrgd 14838*	Prove a subring 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 -> .1. = ( 1r ` I ) )   &    |- ( ph -> .x. = ( .r ` I ) )   &    |- ( ph -> .1. e. D )   &    |- ( ( ph /\ x e. D /\ y e. D ) -> ( x .x. y ) e. D )   &    |- ( ph -> I e. Ring )   =>    |- ( ph -> D e. (SubRing ` I ) )
Theorem	rlmfn 14839	ringLMod is a function. (Contributed by Stefan O'Rear, 6-Dec-2014.)
|- ringLMod Fn _V
Theorem	rlmvalg 14840	Value of the ring module. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- ( W e. V -> (ringLMod ` W ) = ( (subringAlg ` W ) ` ( Base ` W ) ) )
Theorem	rlmbasg 14841	Base set of the ring module. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- ( R e. V -> ( Base ` R ) = ( Base ` (ringLMod ` R ) ) )
Theorem	rlmplusgg 14842	Vector addition in the ring module. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- ( R e. V -> ( +g ` R ) = ( +g ` (ringLMod ` R ) ) )
Theorem	rlm0g 14843	Zero vector in the ring module. (Contributed by Stefan O'Rear, 6-Dec-2014.) (Revised by Mario Carneiro, 2-Oct-2015.)
|- ( R e. V -> ( 0g ` R ) = ( 0g ` (ringLMod ` R ) ) )
Theorem	rlmsubg 14844	Subtraction in the ring module. (Contributed by Thierry Arnoux, 30-Jun-2019.)
|- ( R e. V -> ( -g ` R ) = ( -g ` (ringLMod ` R ) ) )
Theorem	rlmmulrg 14845	Ring multiplication in the ring module. (Contributed by Mario Carneiro, 6-Oct-2015.)
|- ( R e. V -> ( .r ` R ) = ( .r ` (ringLMod ` R ) ) )
Theorem	rlmscabas 14846	Scalars in the ring module have the same base set. (Contributed by Jim Kingdon, 29-Apr-2025.)
|- ( R e. X -> ( Base ` R ) = ( Base ` (Scalar ` (ringLMod ` R ) ) ) )
Theorem	rlmvscag 14847	Scalar multiplication in the ring module. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- ( R e. V -> ( .r ` R ) = ( .s ` (ringLMod ` R ) ) )
Theorem	rlmtopng 14848	Topology component of the ring module. (Contributed by Mario Carneiro, 6-Oct-2015.)
|- ( R e. V -> ( TopOpen ` R ) = ( TopOpen ` (ringLMod ` R ) ) )
Theorem	rlmdsg 14849	Metric component of the ring module. (Contributed by Mario Carneiro, 6-Oct-2015.)
|- ( R e. V -> ( dist ` R ) = ( dist ` (ringLMod ` R ) ) )
Theorem	rlmlmod 14850	The ring module is a module. (Contributed by Stefan O'Rear, 6-Dec-2014.)
|- ( R e. Ring -> (ringLMod ` R ) e. LMod )
Theorem	rlmvnegg 14851	Vector negation in the ring module. (Contributed by Stefan O'Rear, 6-Dec-2014.) (Revised by Mario Carneiro, 5-Jun-2015.)
|- ( R e. V -> ( invg ` R ) = ( invg ` (ringLMod ` R ) ) )
Theorem	ixpsnbasval 14852*	The value of an infinite Cartesian product of the base of a left module over a ring with a singleton. (Contributed by AV, 3-Dec-2018.)
|- ( ( R e. V /\ X e. W ) -> X_ x e. { X } ( Base ` ( ( { X } X. { (ringLMod ` R ) } ) ` x ) ) = { f | ( f Fn { X } /\ ( f ` X ) e. ( Base ` R ) ) } )
7.6.2  Ideals and spans
Syntax	clidl 14853	Ring left-ideal function.
class LIdeal
Syntax	crsp 14854	Ring span function.
class RSpan
Definition	df-lidl 14855	Define the class of left ideals of a given ring. An ideal is a submodule of the ring viewed as a module over itself. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- LIdeal = ( LSubSp o. ringLMod )
Definition	df-rsp 14856	Define the linear span function in a ring (Ideal generator). (Contributed by Stefan O'Rear, 4-Apr-2015.)
|- RSpan = ( LSpan o. ringLMod )
Theorem	lidlvalg 14857	Value of the set of ring ideals. (Contributed by Stefan O'Rear, 31-Mar-2015.)
|- ( W e. V -> (LIdeal ` W ) = ( LSubSp ` (ringLMod ` W ) ) )
Theorem	rspvalg 14858	Value of the ring span function. (Contributed by Stefan O'Rear, 4-Apr-2015.)
|- ( W e. V -> (RSpan ` W ) = ( LSpan ` (ringLMod ` W ) ) )
Theorem	lidlex 14859	Existence of the set of left ideals. (Contributed by Jim Kingdon, 27-Apr-2025.)
|- ( W e. V -> (LIdeal ` W ) e. _V )
Theorem	rspex 14860	Existence of the ring span. (Contributed by Jim Kingdon, 25-Apr-2025.)
|- ( W e. V -> (RSpan ` W ) e. _V )
Theorem	lidlmex 14861	Existence of the set a left ideal is built from (when the ideal is inhabited). (Contributed by Jim Kingdon, 18-Apr-2025.)
|- I = (LIdeal ` W )   =>    |- ( U e. I -> W e. _V )
Theorem	lidlss 14862	An ideal is a subset of the base set. (Contributed by Stefan O'Rear, 28-Mar-2015.)
|- B = ( Base ` W )   &    |- I = (LIdeal ` W )   =>    |- ( U e. I -> U C_ B )
Theorem	lidlssbas 14863	The base set of the restriction of the ring to a (left) ideal is a subset of the base set of the ring. (Contributed by AV, 17-Feb-2020.)
|- L = (LIdeal ` R )   &    |- I = ( R ↾s U )   =>    |- ( U e. L -> ( Base ` I ) C_ ( Base ` R ) )
Theorem	lidlbas 14864	A (left) ideal of a ring is the base set of the restriction of the ring to this ideal. (Contributed by AV, 17-Feb-2020.)
|- L = (LIdeal ` R )   &    |- I = ( R ↾s U )   =>    |- ( U e. L -> ( Base ` I ) = U )
Theorem	islidlm 14865*	Predicate of being a (left) ideal. (Contributed by Stefan O'Rear, 1-Apr-2015.)
|- U = (LIdeal ` R )   &    |- B = ( Base ` R )   &    |- .+ = ( +g ` R )   &    |- .x. = ( .r ` R )   =>    |- ( I e. U <-> ( I C_ B /\ E. j j e. I /\ A. x e. B A. a e. I A. b e. I ( ( x .x. a ) .+ b ) e. I ) )
Theorem	rnglidlmcl 14866	A (left) ideal containing the zero element is closed under left-multiplication by elements of the full non-unital ring. If the ring is not a unital ring, and the ideal does not contain the zero element of the ring, then the closure cannot be proven. (Contributed by AV, 18-Feb-2025.)
|- .0. = ( 0g ` R )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   &    |- U = (LIdeal ` R )   =>    |- ( ( ( R e. Rng /\ I e. U /\ .0. e. I ) /\ ( X e. B /\ Y e. I ) ) -> ( X .x. Y ) e. I )
Theorem	dflidl2rng 14867*	Alternate (the usual textbook) definition of a (left) ideal of a non-unital ring to be a subgroup of the additive group of the ring which is closed under left-multiplication by elements of the full ring. (Contributed by AV, 21-Mar-2025.)
|- U = (LIdeal ` R )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( ( R e. Rng /\ I e. (SubGrp ` R ) ) -> ( I e. U <-> A. x e. B A. y e. I ( x .x. y ) e. I ) )
Theorem	isridlrng 14868*	A right ideal is a left ideal of the opposite non-unital ring. This theorem shows that this definition corresponds to the usual textbook definition of a right ideal of a ring to be a subgroup of the additive group of the ring which is closed under right-multiplication by elements of the full ring. (Contributed by AV, 21-Mar-2025.)
|- U = (LIdeal ` (oppr ` R ) )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( ( R e. Rng /\ I e. (SubGrp ` R ) ) -> ( I e. U <-> A. x e. B A. y e. I ( y .x. x ) e. I ) )
Theorem	lidl0cl 14869	An ideal contains 0. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- U = (LIdeal ` R )   &    |- .0. = ( 0g ` R )   =>    |- ( ( R e. Ring /\ I e. U ) -> .0. e. I )
Theorem	lidlacl 14870	An ideal is closed under addition. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- U = (LIdeal ` R )   &    |- .+ = ( +g ` R )   =>    |- ( ( ( R e. Ring /\ I e. U ) /\ ( X e. I /\ Y e. I ) ) -> ( X .+ Y ) e. I )
Theorem	lidlnegcl 14871	An ideal contains negatives. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- U = (LIdeal ` R )   &    |- N = ( invg ` R )   =>    |- ( ( R e. Ring /\ I e. U /\ X e. I ) -> ( N ` X ) e. I )
Theorem	lidlsubg 14872	An ideal is a subgroup of the additive group. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- U = (LIdeal ` R )   =>    |- ( ( R e. Ring /\ I e. U ) -> I e. (SubGrp ` R ) )
Theorem	lidlsubcl 14873	An ideal is closed under subtraction. (Contributed by Stefan O'Rear, 28-Mar-2015.) (Proof shortened by OpenAI, 25-Mar-2020.)
|- U = (LIdeal ` R )   &    |- .- = ( -g ` R )   =>    |- ( ( ( R e. Ring /\ I e. U ) /\ ( X e. I /\ Y e. I ) ) -> ( X .- Y ) e. I )
Theorem	dflidl2 14874*	Alternate (the usual textbook) definition of a (left) ideal of a ring to be a subgroup of the additive group of the ring which is closed under left-multiplication by elements of the full ring. (Contributed by AV, 13-Feb-2025.) (Proof shortened by AV, 18-Apr-2025.)
|- U = (LIdeal ` R )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( R e. Ring -> ( I e. U <-> ( I e. (SubGrp ` R ) /\ A. x e. B A. y e. I ( x .x. y ) e. I ) ) )
Theorem	lidl0 14875	Every ring contains a zero ideal. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- U = (LIdeal ` R )   &    |- .0. = ( 0g ` R )   =>    |- ( R e. Ring -> { .0. } e. U )
Theorem	lidl1 14876	Every ring contains a unit ideal. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- U = (LIdeal ` R )   &    |- B = ( Base ` R )   =>    |- ( R e. Ring -> B e. U )
Theorem	rspcl 14877	The span of a set of ring elements is an ideal. (Contributed by Stefan O'Rear, 3-Jan-2015.) (Revised by Mario Carneiro, 2-Oct-2015.)
|- K = (RSpan ` R )   &    |- B = ( Base ` R )   &    |- U = (LIdeal ` R )   =>    |- ( ( R e. Ring /\ G C_ B ) -> ( K ` G ) e. U )
Theorem	rspssid 14878	The span of a set of ring elements contains those elements. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- K = (RSpan ` R )   &    |- B = ( Base ` R )   =>    |- ( ( R e. Ring /\ G C_ B ) -> G C_ ( K ` G ) )
Theorem	rsp0 14879	The span of the zero element is the zero ideal. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- K = (RSpan ` R )   &    |- .0. = ( 0g ` R )   =>    |- ( R e. Ring -> ( K ` { .0. } ) = { .0. } )
Theorem	rspssp 14880	The ideal span of a set of elements in a ring is contained in any subring which contains those elements. (Contributed by Stefan O'Rear, 3-Jan-2015.)
|- K = (RSpan ` R )   &    |- U = (LIdeal ` R )   =>    |- ( ( R e. Ring /\ I e. U /\ G C_ I ) -> ( K ` G ) C_ I )
Theorem	lidlrsppropdg 14881*	The left ideals and ring span of a ring depend only on the ring components. Here W is expected to be either B (when closure is available) or _V (when strong equality is available). (Contributed by Mario Carneiro, 14-Jun-2015.)
|- ( ph -> B = ( Base ` K ) )   &    |- ( ph -> B = ( Base ` L ) )   &    |- ( ph -> B C_ W )   &    |- ( ( ph /\ ( x e. W /\ y e. W ) ) -> ( x ( +g ` K ) y ) = ( x ( +g ` L ) y ) )   &    |- ( ( ph /\ ( x e. B /\ y e. B ) ) -> ( x ( .r ` K ) y ) e. W )   &    |- ( ( ph /\ ( x e. B /\ y e. B ) ) -> ( x ( .r ` K ) y ) = ( x ( .r ` L ) y ) )   &    |- ( ph -> K e. X )   &    |- ( ph -> L e. Y )   =>    |- ( ph -> ( (LIdeal ` K ) = (LIdeal ` L ) /\ (RSpan ` K ) = (RSpan ` L ) ) )
Theorem	rnglidlmmgm 14882	The multiplicative group of a (left) ideal of a non-unital ring is a magma. (Contributed by AV, 17-Feb-2020.) Generalization for non-unital rings. The assumption .0. e. U is required because a left ideal of a non-unital ring does not have to be a subgroup. (Revised by AV, 11-Mar-2025.)
|- L = (LIdeal ` R )   &    |- I = ( R ↾s U )   &    |- .0. = ( 0g ` R )   =>    |- ( ( R e. Rng /\ U e. L /\ .0. e. U ) -> (mulGrp ` I ) e. Mgm )
Theorem	rnglidlmsgrp 14883	The multiplicative group of a (left) ideal of a non-unital ring is a semigroup. (Contributed by AV, 17-Feb-2020.) Generalization for non-unital rings. The assumption .0. e. U is required because a left ideal of a non-unital ring does not have to be a subgroup. (Revised by AV, 11-Mar-2025.)
|- L = (LIdeal ` R )   &    |- I = ( R ↾s U )   &    |- .0. = ( 0g ` R )   =>    |- ( ( R e. Rng /\ U e. L /\ .0. e. U ) -> (mulGrp ` I ) e. Smgrp )
Theorem	rnglidlrng 14884	A (left) ideal of a non-unital ring is a non-unital ring. (Contributed by AV, 17-Feb-2020.) Generalization for non-unital rings. The assumption U e. (SubGrp ` R ) is required because a left ideal of a non-unital ring does not have to be a subgroup. (Revised by AV, 11-Mar-2025.)
|- L = (LIdeal ` R )   &    |- I = ( R ↾s U )   =>    |- ( ( R e. Rng /\ U e. L /\ U e. (SubGrp ` R ) ) -> I e. Rng )
7.6.3  Two-sided ideals and quotient rings
Syntax	c2idl 14885	Ring two-sided ideal function.
class 2Ideal
Definition	df-2idl 14886	Define the class of two-sided ideals of a ring. A two-sided ideal is a left ideal which is also a right ideal (or a left ideal over the opposite ring). (Contributed by Mario Carneiro, 14-Jun-2015.)
|- 2Ideal = ( r e. _V |-> ( (LIdeal ` r ) i^i (LIdeal ` (oppr ` r ) ) ) )
Theorem	2idlmex 14887	Existence of the set a two-sided ideal is built from (when the ideal is inhabited). (Contributed by Jim Kingdon, 18-Apr-2025.)
|- T = (2Ideal ` W )   =>    |- ( U e. T -> W e. _V )
Theorem	2idlval 14888	Definition of a two-sided ideal. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- I = (LIdeal ` R )   &    |- O = (oppr ` R )   &    |- J = (LIdeal ` O )   &    |- T = (2Ideal ` R )   =>    |- T = ( I i^i J )
Theorem	2idlvalg 14889	Definition of a two-sided ideal. (Contributed by Mario Carneiro, 14-Jun-2015.)
|- I = (LIdeal ` R )   &    |- O = (oppr ` R )   &    |- J = (LIdeal ` O )   &    |- T = (2Ideal ` R )   =>    |- ( R e. V -> T = ( I i^i J ) )
Theorem	isridl 14890*	A right ideal is a left ideal of the opposite ring. This theorem shows that this definition corresponds to the usual textbook definition of a right ideal of a ring to be a subgroup of the additive group of the ring which is closed under right-multiplication by elements of the full ring. (Contributed by AV, 13-Feb-2025.)
|- U = (LIdeal ` (oppr ` R ) )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( R e. Ring -> ( I e. U <-> ( I e. (SubGrp ` R ) /\ A. x e. B A. y e. I ( y .x. x ) e. I ) ) )
Theorem	2idlelb 14891	Membership in a two-sided ideal. (Contributed by Mario Carneiro, 14-Jun-2015.) (Revised by AV, 20-Feb-2025.)
|- I = (LIdeal ` R )   &    |- O = (oppr ` R )   &    |- J = (LIdeal ` O )   &    |- T = (2Ideal ` R )   =>    |- ( U e. T <-> ( U e. I /\ U e. J ) )
Theorem	2idllidld 14892	A two-sided ideal is a left ideal. (Contributed by Thierry Arnoux, 9-Mar-2025.)
|- ( ph -> I e. (2Ideal ` R ) )   =>    |- ( ph -> I e. (LIdeal ` R ) )
Theorem	2idlridld 14893	A two-sided ideal is a right ideal. (Contributed by Thierry Arnoux, 9-Mar-2025.)
|- ( ph -> I e. (2Ideal ` R ) )   &    |- O = (oppr ` R )   =>    |- ( ph -> I e. (LIdeal ` O ) )
Theorem	df2idl2rng 14894*	Alternate (the usual textbook) definition of a two-sided ideal of a non-unital ring to be a subgroup of the additive group of the ring which is closed under left- and right-multiplication by elements of the full ring. (Contributed by AV, 21-Mar-2025.)
|- U = (2Ideal ` R )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( ( R e. Rng /\ I e. (SubGrp ` R ) ) -> ( I e. U <-> A. x e. B A. y e. I ( ( x .x. y ) e. I /\ ( y .x. x ) e. I ) ) )
Theorem	df2idl2 14895*	Alternate (the usual textbook) definition of a two-sided ideal of a ring to be a subgroup of the additive group of the ring which is closed under left- and right-multiplication by elements of the full ring. (Contributed by AV, 13-Feb-2025.) (Proof shortened by AV, 18-Apr-2025.)
|- U = (2Ideal ` R )   &    |- B = ( Base ` R )   &    |- .x. = ( .r ` R )   =>    |- ( R e. Ring -> ( I e. U <-> ( I e. (SubGrp ` R ) /\ A. x e. B A. y e. I ( ( x .x. y ) e. I /\ ( y .x. x ) e. I ) ) ) )
Theorem	ridl0 14896	Every ring contains a zero right ideal. (Contributed by AV, 13-Feb-2025.)
|- U = (LIdeal ` (oppr ` R ) )   &    |- .0. = ( 0g ` R )   =>    |- ( R e. Ring -> { .0. } e. U )
Theorem	ridl1 14897	Every ring contains a unit right ideal. (Contributed by AV, 13-Feb-2025.)
|- U = (LIdeal ` (oppr ` R ) )   &    |- B = ( Base ` R )   =>    |- ( R e. Ring -> B e. U )
Theorem	2idl0 14898	Every ring contains a zero two-sided ideal. (Contributed by AV, 13-Feb-2025.)
|- I = (2Ideal ` R )   &    |- .0. = ( 0g ` R )   =>    |- ( R e. Ring -> { .0. } e. I )
Theorem	2idl1 14899	Every ring contains a unit two-sided ideal. (Contributed by AV, 13-Feb-2025.)
|- I = (2Ideal ` R )   &    |- B = ( Base ` R )   =>    |- ( R e. Ring -> B e. I )
Theorem	2idlss 14900	A two-sided ideal is a subset of the base set. (Contributed by Mario Carneiro, 14-Jun-2015.) (Revised by AV, 20-Feb-2025.) (Proof shortened by AV, 13-Mar-2025.)
|- B = ( Base ` W )   &    |- I = (2Ideal ` W )   =>    |- ( U e. I -> U C_ B )