P. 129 of Theorem List - Intuitionistic Logic Explorer

Theorem List for Intuitionistic Logic Explorer - 12801-12900   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	slotex 12801	Existence of slot value. A corollary of slotslfn 12800. (Contributed by Jim Kingdon, 12-Feb-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   =>    |- ( A e. V -> ( E ` A ) e. _V )
Theorem	strndxid 12802	The value of a structure component extractor is the value of the corresponding slot of the structure. (Contributed by AV, 13-Mar-2020.)
|- ( ph -> S e. V )   &    |- E = Slot N   &    |- N e. NN   =>    |- ( ph -> ( S ` ( E ` ndx ) ) = ( E ` S ) )
Theorem	reldmsets 12803	The structure override operator is a proper operator. (Contributed by Stefan O'Rear, 29-Jan-2015.)
|- Rel dom sSet
Theorem	setsvalg 12804	Value of the structure replacement function. (Contributed by Mario Carneiro, 30-Apr-2015.)
|- ( ( S e. V /\ A e. W ) -> ( S sSet A ) = ( ( S |` ( _V \ dom { A } ) ) u. { A } ) )
Theorem	setsvala 12805	Value of the structure replacement function. (Contributed by Mario Carneiro, 1-Dec-2014.) (Revised by Jim Kingdon, 20-Jan-2023.)
|- ( ( S e. V /\ A e. X /\ B e. W ) -> ( S sSet <. A , B >. ) = ( ( S |` ( _V \ { A } ) ) u. { <. A , B >. } ) )
Theorem	setsex 12806	Applying the structure replacement function yields a set. (Contributed by Jim Kingdon, 22-Jan-2023.)
|- ( ( S e. V /\ A e. X /\ B e. W ) -> ( S sSet <. A , B >. ) e. _V )
Theorem	strsetsid 12807	Value of the structure replacement function. (Contributed by AV, 14-Mar-2020.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- E = Slot ( E ` ndx )   &    |- ( ph -> S Struct <. M , N >. )   &    |- ( ph -> Fun S )   &    |- ( ph -> ( E ` ndx ) e. dom S )   =>    |- ( ph -> S = ( S sSet <. ( E ` ndx ) , ( E ` S ) >. ) )
Theorem	fvsetsid 12808	The value of the structure replacement function for its first argument is its second argument. (Contributed by SO, 12-Jul-2018.)
|- ( ( F e. V /\ X e. W /\ Y e. U ) -> ( ( F sSet <. X , Y >. ) ` X ) = Y )
Theorem	setsfun 12809	A structure with replacement is a function if the original structure is a function. (Contributed by AV, 7-Jun-2021.)
|- ( ( ( G e. V /\ Fun G ) /\ ( I e. U /\ E e. W ) ) -> Fun ( G sSet <. I , E >. ) )
Theorem	setsfun0 12810	A structure with replacement without the empty set is a function if the original structure without the empty set is a function. This variant of setsfun 12809 is useful for proofs based on isstruct2r 12785 which requires Fun ( F \ { (/) } ) for F to be an extensible structure. (Contributed by AV, 7-Jun-2021.)
|- ( ( ( G e. V /\ Fun ( G \ { (/) } ) ) /\ ( I e. U /\ E e. W ) ) -> Fun ( ( G sSet <. I , E >. ) \ { (/) } ) )
Theorem	setsn0fun 12811	The value of the structure replacement function (without the empty set) is a function if the structure (without the empty set) is a function. (Contributed by AV, 7-Jun-2021.) (Revised by AV, 16-Nov-2021.)
|- ( ph -> S Struct X )   &    |- ( ph -> I e. U )   &    |- ( ph -> E e. W )   =>    |- ( ph -> Fun ( ( S sSet <. I , E >. ) \ { (/) } ) )
Theorem	setsresg 12812	The structure replacement function does not affect the value of S away from A. (Contributed by Mario Carneiro, 1-Dec-2014.) (Revised by Jim Kingdon, 22-Jan-2023.)
|- ( ( S e. V /\ A e. W /\ B e. X ) -> ( ( S sSet <. A , B >. ) |` ( _V \ { A } ) ) = ( S |` ( _V \ { A } ) ) )
Theorem	setsabsd 12813	Replacing the same components twice yields the same as the second setting only. (Contributed by Mario Carneiro, 2-Dec-2014.) (Revised by Jim Kingdon, 22-Jan-2023.)
|- ( ph -> S e. V )   &    |- ( ph -> A e. W )   &    |- ( ph -> B e. X )   &    |- ( ph -> C e. U )   =>    |- ( ph -> ( ( S sSet <. A , B >. ) sSet <. A , C >. ) = ( S sSet <. A , C >. ) )
Theorem	setscom 12814	Different components can be set in any order. (Contributed by Mario Carneiro, 5-Dec-2014.) (Revised by Mario Carneiro, 30-Apr-2015.)
|- A e. _V   &    |- B e. _V   =>    |- ( ( ( S e. V /\ A =/= B ) /\ ( C e. W /\ D e. X ) ) -> ( ( S sSet <. A , C >. ) sSet <. B , D >. ) = ( ( S sSet <. B , D >. ) sSet <. A , C >. ) )
Theorem	setscomd 12815	Different components can be set in any order. (Contributed by Jim Kingdon, 20-Feb-2025.)
|- ( ph -> A e. Y )   &    |- ( ph -> B e. Z )   &    |- ( ph -> S e. V )   &    |- ( ph -> A =/= B )   &    |- ( ph -> C e. W )   &    |- ( ph -> D e. X )   =>    |- ( ph -> ( ( S sSet <. A , C >. ) sSet <. B , D >. ) = ( ( S sSet <. B , D >. ) sSet <. A , C >. ) )
Theorem	strslfvd 12816	Deduction version of strslfv 12819. (Contributed by Mario Carneiro, 15-Nov-2014.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( ph -> S e. V )   &    |- ( ph -> Fun S )   &    |- ( ph -> <. ( E ` ndx ) , C >. e. S )   =>    |- ( ph -> C = ( E ` S ) )
Theorem	strslfv2d 12817	Deduction version of strslfv 12819. (Contributed by Mario Carneiro, 30-Apr-2015.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( ph -> S e. V )   &    |- ( ph -> Fun `' `' S )   &    |- ( ph -> <. ( E ` ndx ) , C >. e. S )   &    |- ( ph -> C e. W )   =>    |- ( ph -> C = ( E ` S ) )
Theorem	strslfv2 12818	A variation on strslfv 12819 to avoid asserting that S itself is a function, which involves sethood of all the ordered pair components of S. (Contributed by Mario Carneiro, 30-Apr-2015.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- S e. _V   &    |- Fun `' `' S   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- <. ( E ` ndx ) , C >. e. S   =>    |- ( C e. V -> C = ( E ` S ) )
Theorem	strslfv 12819	Extract a structure component C (such as the base set) from a structure S with a component extractor E (such as the base set extractor df-base 12780). By virtue of ndxslid 12799, this can be done without having to refer to the hard-coded numeric index of E. (Contributed by Mario Carneiro, 6-Oct-2013.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- S Struct X   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- { <. ( E ` ndx ) , C >. } C_ S   =>    |- ( C e. V -> C = ( E ` S ) )
Theorem	strslfv3 12820	Variant on strslfv 12819 for large structures. (Contributed by Mario Carneiro, 10-Jan-2017.) (Revised by Jim Kingdon, 30-Jan-2023.)
|- ( ph -> U = S )   &    |- ( ph -> S Struct X )   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( ph -> { <. ( E ` ndx ) , C >. } C_ S )   &    |- ( ph -> C e. V )   &    |- A = ( E ` U )   =>    |- ( ph -> A = C )
Theorem	strslssd 12821	Deduction version of strslss 12822. (Contributed by Mario Carneiro, 15-Nov-2014.) (Revised by Mario Carneiro, 30-Apr-2015.) (Revised by Jim Kingdon, 31-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( ph -> T e. V )   &    |- ( ph -> Fun T )   &    |- ( ph -> S C_ T )   &    |- ( ph -> <. ( E ` ndx ) , C >. e. S )   =>    |- ( ph -> ( E ` T ) = ( E ` S ) )
Theorem	strslss 12822	Propagate component extraction to a structure T from a subset structure S. (Contributed by Mario Carneiro, 11-Oct-2013.) (Revised by Jim Kingdon, 31-Jan-2023.)
|- T e. _V   &    |- Fun T   &    |- S C_ T   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- <. ( E ` ndx ) , C >. e. S   =>    |- ( E ` T ) = ( E ` S )
Theorem	strsl0 12823	All components of the empty set are empty sets. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Jim Kingdon, 31-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   =>    |- (/) = ( E ` (/) )
Theorem	base0 12824	The base set of the empty structure. (Contributed by David A. Wheeler, 7-Jul-2016.)
|- (/) = ( Base ` (/) )
Theorem	setsslid 12825	Value of the structure replacement function at a replaced index. (Contributed by Mario Carneiro, 1-Dec-2014.) (Revised by Jim Kingdon, 24-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   =>    |- ( ( W e. A /\ C e. V ) -> C = ( E ` ( W sSet <. ( E ` ndx ) , C >. ) ) )
Theorem	setsslnid 12826	Value of the structure replacement function at an untouched index. (Contributed by Mario Carneiro, 1-Dec-2014.) (Revised by Jim Kingdon, 24-Jan-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( E ` ndx ) =/= D   &    |- D e. NN   =>    |- ( ( W e. A /\ C e. V ) -> ( E ` W ) = ( E ` ( W sSet <. D , C >. ) ) )
Theorem	baseval 12827	Value of the base set extractor. (Normally it is preferred to work with ( Base ` ndx ) rather than the hard-coded 1 in order to make structure theorems portable. This is an example of how to obtain it when needed.) (New usage is discouraged.) (Contributed by NM, 4-Sep-2011.)
|- K e. _V   =>    |- ( Base ` K ) = ( K ` 1 )
Theorem	baseid 12828	Utility theorem: index-independent form of df-base 12780. (Contributed by NM, 20-Oct-2012.)
|- Base = Slot ( Base ` ndx )
Theorem	basendx 12829	Index value of the base set extractor. Use of this theorem is discouraged since the particular value 1 for the index is an implementation detail. It is generally sufficient to work with ( Base ` ndx ) and use theorems such as baseid 12828 and basendxnn 12830. The main circumstance in which it is necessary to look at indices directly is when showing that a set of indices are disjoint, in proofs such as lmodstrd 12938. Although we have a few theorems such as basendxnplusgndx 12899, we do not intend to add such theorems for every pair of indices (which would be quadradically many in the number of indices). (New usage is discouraged.) (Contributed by Mario Carneiro, 2-Aug-2013.)
|- ( Base ` ndx ) = 1
Theorem	basendxnn 12830	The index value of the base set extractor is a positive integer. This property should be ensured for every concrete coding because otherwise it could not be used in an extensible structure (slots must be positive integers). (Contributed by AV, 23-Sep-2020.)
|- ( Base ` ndx ) e. NN
Theorem	baseslid 12831	The base set extractor is a slot. (Contributed by Jim Kingdon, 31-Jan-2023.)
|- ( Base = Slot ( Base ` ndx ) /\ ( Base ` ndx ) e. NN )
Theorem	basfn 12832	The base set extractor is a function on _V. (Contributed by Stefan O'Rear, 8-Jul-2015.)
|- Base Fn _V
Theorem	basmex 12833	A structure whose base is inhabited is a set. (Contributed by Jim Kingdon, 18-Nov-2024.)
|- B = ( Base ` G )   =>    |- ( A e. B -> G e. _V )
Theorem	basmexd 12834	A structure whose base is inhabited is a set. (Contributed by Jim Kingdon, 28-Nov-2024.)
|- ( ph -> B = ( Base ` G ) )   &    |- ( ph -> A e. B )   =>    |- ( ph -> G e. _V )
Theorem	basm 12835*	A structure whose base is inhabited is inhabited. (Contributed by Jim Kingdon, 14-Jun-2025.)
|- B = ( Base ` G )   =>    |- ( A e. B -> E. j j e. G )
Theorem	relelbasov 12836	Utility theorem: reverse closure for any structure defined as a two-argument function. (Contributed by Mario Carneiro, 3-Oct-2015.)
|- Rel dom O   &    |- Rel O   &    |- S = ( X O Y )   &    |- B = ( Base ` S )   =>    |- ( A e. B -> ( X e. _V /\ Y e. _V ) )
Theorem	reldmress 12837	The structure restriction is a proper operator, so it can be used with ovprc1 5980. (Contributed by Stefan O'Rear, 29-Nov-2014.)
|- Rel dom ↾s
Theorem	ressvalsets 12838	Value of structure restriction. (Contributed by Jim Kingdon, 16-Jan-2025.)
|- ( ( W e. X /\ A e. Y ) -> ( W ↾s A ) = ( W sSet <. ( Base ` ndx ) , ( A i^i ( Base ` W ) ) >. ) )
Theorem	ressex 12839	Existence of structure restriction. (Contributed by Jim Kingdon, 16-Jan-2025.)
|- ( ( W e. X /\ A e. Y ) -> ( W ↾s A ) e. _V )
Theorem	ressval2 12840	Value of nontrivial structure restriction. (Contributed by Stefan O'Rear, 29-Nov-2014.)
|- R = ( W ↾s A )   &    |- B = ( Base ` W )   =>    |- ( ( -. B C_ A /\ W e. X /\ A e. Y ) -> R = ( W sSet <. ( Base ` ndx ) , ( A i^i B ) >. ) )
Theorem	ressbasd 12841	Base set of a structure restriction. (Contributed by Stefan O'Rear, 26-Nov-2014.) (Proof shortened by AV, 7-Nov-2024.)
|- ( ph -> R = ( W ↾s A ) )   &    |- ( ph -> B = ( Base ` W ) )   &    |- ( ph -> W e. X )   &    |- ( ph -> A e. V )   =>    |- ( ph -> ( A i^i B ) = ( Base ` R ) )
Theorem	ressbas2d 12842	Base set of a structure restriction. (Contributed by Mario Carneiro, 2-Dec-2014.)
|- ( ph -> R = ( W ↾s A ) )   &    |- ( ph -> B = ( Base ` W ) )   &    |- ( ph -> W e. X )   &    |- ( ph -> A C_ B )   =>    |- ( ph -> A = ( Base ` R ) )
Theorem	ressbasssd 12843	The base set of a restriction is a subset of the base set of the original structure. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 30-Apr-2015.)
|- ( ph -> R = ( W ↾s A ) )   &    |- ( ph -> B = ( Base ` W ) )   &    |- ( ph -> W e. X )   &    |- ( ph -> A e. V )   =>    |- ( ph -> ( Base ` R ) C_ B )
Theorem	ressbasid 12844	The trivial structure restriction leaves the base set unchanged. (Contributed by Jim Kingdon, 29-Apr-2025.)
|- B = ( Base ` W )   =>    |- ( W e. V -> ( Base ` ( W ↾s B ) ) = B )
Theorem	strressid 12845	Behavior of trivial restriction. (Contributed by Stefan O'Rear, 29-Nov-2014.) (Revised by Jim Kingdon, 17-Jan-2025.)
|- ( ph -> B = ( Base ` W ) )   &    |- ( ph -> W Struct <. M , N >. )   &    |- ( ph -> Fun W )   &    |- ( ph -> ( Base ` ndx ) e. dom W )   =>    |- ( ph -> ( W ↾s B ) = W )
Theorem	ressval3d 12846	Value of structure restriction, deduction version. (Contributed by AV, 14-Mar-2020.) (Revised by Jim Kingdon, 17-Jan-2025.)
|- R = ( S ↾s A )   &    |- B = ( Base ` S )   &    |- E = ( Base ` ndx )   &    |- ( ph -> S e. V )   &    |- ( ph -> Fun S )   &    |- ( ph -> E e. dom S )   &    |- ( ph -> A C_ B )   =>    |- ( ph -> R = ( S sSet <. E , A >. ) )
Theorem	resseqnbasd 12847	The components of an extensible structure except the base set remain unchanged on a structure restriction. (Contributed by Mario Carneiro, 26-Nov-2014.) (Revised by Mario Carneiro, 2-Dec-2014.) (Revised by AV, 19-Oct-2024.)
|- R = ( W ↾s A )   &    |- C = ( E ` W )   &    |- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( E ` ndx ) =/= ( Base ` ndx )   &    |- ( ph -> W e. X )   &    |- ( ph -> A e. V )   =>    |- ( ph -> C = ( E ` R ) )
Theorem	ressinbasd 12848	Restriction only cares about the part of the second set which intersects the base of the first. (Contributed by Stefan O'Rear, 29-Nov-2014.)
|- ( ph -> B = ( Base ` W ) )   &    |- ( ph -> A e. X )   &    |- ( ph -> W e. V )   =>    |- ( ph -> ( W ↾s A ) = ( W ↾s ( A i^i B ) ) )
Theorem	ressressg 12849	Restriction composition law. (Contributed by Stefan O'Rear, 29-Nov-2014.) (Proof shortened by Mario Carneiro, 2-Dec-2014.)
|- ( ( A e. X /\ B e. Y /\ W e. Z ) -> ( ( W ↾s A ) ↾s B ) = ( W ↾s ( A i^i B ) ) )
Theorem	ressabsg 12850	Restriction absorption law. (Contributed by Mario Carneiro, 12-Jun-2015.)
|- ( ( A e. X /\ B C_ A /\ W e. Y ) -> ( ( W ↾s A ) ↾s B ) = ( W ↾s B ) )
6.1.2  Slot definitions
Syntax	cplusg 12851	Extend class notation with group (addition) operation.
class +g
Syntax	cmulr 12852	Extend class notation with ring multiplication.
class .r
Syntax	cstv 12853	Extend class notation with involution.
class *r
Syntax	csca 12854	Extend class notation with scalar field.
class Scalar
Syntax	cvsca 12855	Extend class notation with scalar product.
class .s
Syntax	cip 12856	Extend class notation with Hermitian form (inner product).
class .i
Syntax	cts 12857	Extend class notation with the topology component of a topological space.
class TopSet
Syntax	cple 12858	Extend class notation with "less than or equal to" for posets.
class le
Syntax	coc 12859	Extend class notation with the class of orthocomplementation extractors.
class oc
Syntax	cds 12860	Extend class notation with the metric space distance function.
class dist
Syntax	cunif 12861	Extend class notation with the uniform structure.
class UnifSet
Syntax	chom 12862	Extend class notation with the hom-set structure.
class Hom
Syntax	cco 12863	Extend class notation with the composition operation.
class comp
Definition	df-plusg 12864	Define group operation. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- +g = Slot 2
Definition	df-mulr 12865	Define ring multiplication. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- .r = Slot 3
Definition	df-starv 12866	Define the involution function of a *-ring. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- *r = Slot 4
Definition	df-sca 12867	Define scalar field component of a vector space v. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- Scalar = Slot 5
Definition	df-vsca 12868	Define scalar product. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- .s = Slot 6
Definition	df-ip 12869	Define Hermitian form (inner product). (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- .i = Slot 8
Definition	df-tset 12870	Define the topology component of a topological space (structure). (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- TopSet = Slot 9
Definition	df-ple 12871	Define "less than or equal to" ordering extractor for posets and related structures. We use ; 1 0 for the index to avoid conflict with 1 through 9 used for other purposes. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.) (Revised by AV, 9-Sep-2021.)
|- le = Slot ; 1 0
Definition	df-ocomp 12872	Define the orthocomplementation extractor for posets and related structures. (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- oc = Slot ; 1 1
Definition	df-ds 12873	Define the distance function component of a metric space (structure). (Contributed by NM, 4-Sep-2011.) (Revised by Mario Carneiro, 14-Aug-2015.)
|- dist = Slot ; 1 2
Definition	df-unif 12874	Define the uniform structure component of a uniform space. (Contributed by Mario Carneiro, 14-Aug-2015.)
|- UnifSet = Slot ; 1 3
Definition	df-hom 12875	Define the hom-set component of a category. (Contributed by Mario Carneiro, 2-Jan-2017.)
|- Hom = Slot ; 1 4
Definition	df-cco 12876	Define the composition operation of a category. (Contributed by Mario Carneiro, 2-Jan-2017.)
|- comp = Slot ; 1 5
Theorem	strleund 12877	Combine two structures into one. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 27-Jan-2023.)
|- ( ph -> F Struct <. A , B >. )   &    |- ( ph -> G Struct <. C , D >. )   &    |- ( ph -> B < C )   =>    |- ( ph -> ( F u. G ) Struct <. A , D >. )
Theorem	strleun 12878	Combine two structures into one. (Contributed by Mario Carneiro, 29-Aug-2015.)
|- F Struct <. A , B >.   &    |- G Struct <. C , D >.   &    |- B < C   =>    |- ( F u. G ) Struct <. A , D >.
Theorem	strext 12879	Extending the upper range of a structure. This works because when we say that a structure has components in A ... C we are not saying that every slot in that range is present, just that all the slots that are present are within that range. (Contributed by Jim Kingdon, 26-Feb-2025.)
|- ( ph -> F Struct <. A , B >. )   &    |- ( ph -> C e. ( ZZ>= ` B ) )   =>    |- ( ph -> F Struct <. A , C >. )
Theorem	strle1g 12880	Make a structure from a singleton. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 27-Jan-2023.)
|- I e. NN   &    |- A = I   =>    |- ( X e. V -> { <. A , X >. } Struct <. I , I >. )
Theorem	strle2g 12881	Make a structure from a pair. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 27-Jan-2023.)
|- I e. NN   &    |- A = I   &    |- I < J   &    |- J e. NN   &    |- B = J   =>    |- ( ( X e. V /\ Y e. W ) -> { <. A , X >. , <. B , Y >. } Struct <. I , J >. )
Theorem	strle3g 12882	Make a structure from a triple. (Contributed by Mario Carneiro, 29-Aug-2015.)
|- I e. NN   &    |- A = I   &    |- I < J   &    |- J e. NN   &    |- B = J   &    |- J < K   &    |- K e. NN   &    |- C = K   =>    |- ( ( X e. V /\ Y e. W /\ Z e. P ) -> { <. A , X >. , <. B , Y >. , <. C , Z >. } Struct <. I , K >. )
Theorem	plusgndx 12883	Index value of the df-plusg 12864 slot. (Contributed by Mario Carneiro, 14-Aug-2015.)
|- ( +g ` ndx ) = 2
Theorem	plusgid 12884	Utility theorem: index-independent form of df-plusg 12864. (Contributed by NM, 20-Oct-2012.)
|- +g = Slot ( +g ` ndx )
Theorem	plusgndxnn 12885	The index of the slot for the group operation in an extensible structure is a positive integer. (Contributed by AV, 17-Oct-2024.)
|- ( +g ` ndx ) e. NN
Theorem	plusgslid 12886	Slot property of +g. (Contributed by Jim Kingdon, 3-Feb-2023.)
|- ( +g = Slot ( +g ` ndx ) /\ ( +g ` ndx ) e. NN )
Theorem	basendxltplusgndx 12887	The index of the slot for the base set is less then the index of the slot for the group operation in an extensible structure. (Contributed by AV, 17-Oct-2024.)
|- ( Base ` ndx ) < ( +g ` ndx )
Theorem	opelstrsl 12888	The slot of a structure which contains an ordered pair for that slot. (Contributed by Jim Kingdon, 5-Feb-2023.)
|- ( E = Slot ( E ` ndx ) /\ ( E ` ndx ) e. NN )   &    |- ( ph -> S Struct X )   &    |- ( ph -> V e. Y )   &    |- ( ph -> <. ( E ` ndx ) , V >. e. S )   =>    |- ( ph -> V = ( E ` S ) )
Theorem	opelstrbas 12889	The base set of a structure with a base set. (Contributed by AV, 10-Nov-2021.)
|- ( ph -> S Struct X )   &    |- ( ph -> V e. Y )   &    |- ( ph -> <. ( Base ` ndx ) , V >. e. S )   =>    |- ( ph -> V = ( Base ` S ) )
Theorem	1strstrg 12890	A constructed one-slot structure. (Contributed by AV, 27-Mar-2020.) (Revised by Jim Kingdon, 28-Jan-2023.)
|- G = { <. ( Base ` ndx ) , B >. }   =>    |- ( B e. V -> G Struct <. 1 , 1 >. )
Theorem	1strbas 12891	The base set of a constructed one-slot structure. (Contributed by AV, 27-Mar-2020.)
|- G = { <. ( Base ` ndx ) , B >. }   =>    |- ( B e. V -> B = ( Base ` G ) )
Theorem	2strstrndx 12892	A constructed two-slot structure not depending on the hard-coded index value of the base set. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 14-Dec-2025.)
|- G = { <. ( Base ` ndx ) , B >. , <. N , .+ >. }   &    |- ( Base ` ndx ) < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> G Struct <. ( Base ` ndx ) , N >. )
Theorem	2strstrg 12893	A constructed two-slot structure. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 28-Jan-2023.) Use 2strstrndx 12892 instead. (New usage is discouraged.)
|- G = { <. ( Base ` ndx ) , B >. , <. ( E ` ndx ) , .+ >. }   &    |- E = Slot N   &    |- 1 < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> G Struct <. 1 , N >. )
Theorem	2strbasg 12894	The base set of a constructed two-slot structure. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 28-Jan-2023.)
|- G = { <. ( Base ` ndx ) , B >. , <. ( E ` ndx ) , .+ >. }   &    |- E = Slot N   &    |- 1 < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> B = ( Base ` G ) )
Theorem	2stropg 12895	The other slot of a constructed two-slot structure. (Contributed by Mario Carneiro, 29-Aug-2015.) (Revised by Jim Kingdon, 28-Jan-2023.)
|- G = { <. ( Base ` ndx ) , B >. , <. ( E ` ndx ) , .+ >. }   &    |- E = Slot N   &    |- 1 < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> .+ = ( E ` G ) )
Theorem	2strstr1g 12896	A constructed two-slot structure. Version of 2strstrg 12893 not depending on the hard-coded index value of the base set. (Contributed by AV, 22-Sep-2020.) (Revised by Jim Kingdon, 2-Feb-2023.)
|- G = { <. ( Base ` ndx ) , B >. , <. N , .+ >. }   &    |- ( Base ` ndx ) < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> G Struct <. ( Base ` ndx ) , N >. )
Theorem	2strbas1g 12897	The base set of a constructed two-slot structure. Version of 2strbasg 12894 not depending on the hard-coded index value of the base set. (Contributed by AV, 22-Sep-2020.) (Revised by Jim Kingdon, 2-Feb-2023.)
|- G = { <. ( Base ` ndx ) , B >. , <. N , .+ >. }   &    |- ( Base ` ndx ) < N   &    |- N e. NN   =>    |- ( ( B e. V /\ .+ e. W ) -> B = ( Base ` G ) )
Theorem	2strop1g 12898	The other slot of a constructed two-slot structure. Version of 2stropg 12895 not depending on the hard-coded index value of the base set. (Contributed by AV, 22-Sep-2020.) (Revised by Jim Kingdon, 2-Feb-2023.)
|- G = { <. ( Base ` ndx ) , B >. , <. N , .+ >. }   &    |- ( Base ` ndx ) < N   &    |- N e. NN   &    |- E = Slot N   =>    |- ( ( B e. V /\ .+ e. W ) -> .+ = ( E ` G ) )
Theorem	basendxnplusgndx 12899	The slot for the base set is not the slot for the group operation in an extensible structure. (Contributed by AV, 14-Nov-2021.)
|- ( Base ` ndx ) =/= ( +g ` ndx )
Theorem	grpstrg 12900	A constructed group is a structure on 1 ... 2. (Contributed by Mario Carneiro, 28-Sep-2013.) (Revised by Mario Carneiro, 30-Apr-2015.)
|- G = { <. ( Base ` ndx ) , B >. , <. ( +g ` ndx ) , .+ >. }   =>    |- ( ( B e. V /\ .+ e. W ) -> G Struct <. 1 , 2 >. )