P. 59 of Theorem List - Intuitionistic Logic Explorer

Theorem List for Intuitionistic Logic Explorer - 5801-5900   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	dff4im 5801*	Property of a mapping. (Contributed by Jim Kingdon, 4-Jan-2019.)
|- ( F : A --> B -> ( F C_ ( A X. B ) /\ A. x e. A E! y e. B x F y ) )
Theorem	dffo3 5802*	An onto mapping expressed in terms of function values. (Contributed by NM, 29-Oct-2006.)
|- ( F : A -onto-> B <-> ( F : A --> B /\ A. y e. B E. x e. A y = ( F ` x ) ) )
Theorem	dffo4 5803*	Alternate definition of an onto mapping. (Contributed by NM, 20-Mar-2007.)
|- ( F : A -onto-> B <-> ( F : A --> B /\ A. y e. B E. x e. A x F y ) )
Theorem	dffo5 5804*	Alternate definition of an onto mapping. (Contributed by NM, 20-Mar-2007.)
|- ( F : A -onto-> B <-> ( F : A --> B /\ A. y e. B E. x x F y ) )
Theorem	fmpt 5805*	Functionality of the mapping operation. (Contributed by Mario Carneiro, 26-Jul-2013.) (Revised by Mario Carneiro, 31-Aug-2015.)
|- F = ( x e. A |-> C )   =>    |- ( A. x e. A C e. B <-> F : A --> B )
Theorem	f1ompt 5806*	Express bijection for a mapping operation. (Contributed by Mario Carneiro, 30-May-2015.) (Revised by Mario Carneiro, 4-Dec-2016.)
|- F = ( x e. A |-> C )   =>    |- ( F : A -1-1-onto-> B <-> ( A. x e. A C e. B /\ A. y e. B E! x e. A y = C ) )
Theorem	fmpti 5807*	Functionality of the mapping operation. (Contributed by NM, 19-Mar-2005.) (Revised by Mario Carneiro, 1-Sep-2015.)
|- F = ( x e. A |-> C )   &    |- ( x e. A -> C e. B )   =>    |- F : A --> B
Theorem	fvmptelcdm 5808*	The value of a function at a point of its domain belongs to its codomain. (Contributed by Glauco Siliprandi, 26-Jun-2021.)
|- ( ph -> ( x e. A |-> B ) : A --> C )   =>    |- ( ( ph /\ x e. A ) -> B e. C )
Theorem	fmptd 5809*	Domain and codomain of the mapping operation; deduction form. (Contributed by Mario Carneiro, 13-Jan-2013.)
|- ( ( ph /\ x e. A ) -> B e. C )   &    |- F = ( x e. A |-> B )   =>    |- ( ph -> F : A --> C )
Theorem	fmpttd 5810*	Version of fmptd 5809 with inlined definition. Domain and codomain of the mapping operation; deduction form. (Contributed by Glauco Siliprandi, 23-Oct-2021.) (Proof shortened by BJ, 16-Aug-2022.)
|- ( ( ph /\ x e. A ) -> B e. C )   =>    |- ( ph -> ( x e. A |-> B ) : A --> C )
Theorem	fmpt3d 5811*	Domain and codomain of the mapping operation; deduction form. (Contributed by Thierry Arnoux, 4-Jun-2017.)
|- ( ph -> F = ( x e. A |-> B ) )   &    |- ( ( ph /\ x e. A ) -> B e. C )   =>    |- ( ph -> F : A --> C )
Theorem	fmptdf 5812*	A version of fmptd 5809 using bound-variable hypothesis instead of a distinct variable condition for ph. (Contributed by Glauco Siliprandi, 29-Jun-2017.)
|- F/ x ph   &    |- ( ( ph /\ x e. A ) -> B e. C )   &    |- F = ( x e. A |-> B )   =>    |- ( ph -> F : A --> C )
Theorem	ffnfv 5813*	A function maps to a class to which all values belong. (Contributed by NM, 3-Dec-2003.)
|- ( F : A --> B <-> ( F Fn A /\ A. x e. A ( F ` x ) e. B ) )
Theorem	ffnfvf 5814	A function maps to a class to which all values belong. This version of ffnfv 5813 uses bound-variable hypotheses instead of distinct variable conditions. (Contributed by NM, 28-Sep-2006.)
|- F/_ x A   &    |- F/_ x B   &    |- F/_ x F   =>    |- ( F : A --> B <-> ( F Fn A /\ A. x e. A ( F ` x ) e. B ) )
Theorem	fnfvrnss 5815*	An upper bound for range determined by function values. (Contributed by NM, 8-Oct-2004.)
|- ( ( F Fn A /\ A. x e. A ( F ` x ) e. B ) -> ran F C_ B )
Theorem	rnmptss 5816*	The range of an operation given by the maps-to notation as a subset. (Contributed by Thierry Arnoux, 24-Sep-2017.)
|- F = ( x e. A |-> B )   =>    |- ( A. x e. A B e. C -> ran F C_ C )
Theorem	fmpt2d 5817*	Domain and codomain of the mapping operation; deduction form. (Contributed by NM, 27-Dec-2014.)
|- ( ( ph /\ x e. A ) -> B e. V )   &    |- ( ph -> F = ( x e. A |-> B ) )   &    |- ( ( ph /\ y e. A ) -> ( F ` y ) e. C )   =>    |- ( ph -> F : A --> C )
Theorem	ffvresb 5818*	A necessary and sufficient condition for a restricted function. (Contributed by Mario Carneiro, 14-Nov-2013.)
|- ( Fun F -> ( ( F |` A ) : A --> B <-> A. x e. A ( x e. dom F /\ ( F ` x ) e. B ) ) )
Theorem	resflem 5819*	A lemma to bound the range of a restriction. The conclusion would also hold with ( X i^i Y ) in place of Y (provided x does not occur in X). If that stronger result is needed, it is however simpler to use the instance of resflem 5819 where ( X i^i Y ) is substituted for Y (in both the conclusion and the third hypothesis). (Contributed by BJ, 4-Jul-2022.)
|- ( ph -> F : V --> X )   &    |- ( ph -> A C_ V )   &    |- ( ( ph /\ x e. A ) -> ( F ` x ) e. Y )   =>    |- ( ph -> ( F |` A ) : A --> Y )
Theorem	f1oresrab 5820*	Build a bijection between restricted abstract builders, given a bijection between the base classes, deduction version. (Contributed by Thierry Arnoux, 17-Aug-2018.)
|- F = ( x e. A |-> C )   &    |- ( ph -> F : A -1-1-onto-> B )   &    |- ( ( ph /\ x e. A /\ y = C ) -> ( ch <-> ps ) )   =>    |- ( ph -> ( F |` { x e. A | ps } ) : { x e. A | ps } -1-1-onto-> { y e. B | ch } )
Theorem	fmptco 5821*	Composition of two functions expressed as ordered-pair class abstractions. If F has the equation ( x + 2 ) and G the equation ( 3 * z ) then ( G o. F ) has the equation ( 3 * ( x + 2 ) ) . (Contributed by FL, 21-Jun-2012.) (Revised by Mario Carneiro, 24-Jul-2014.)
|- ( ( ph /\ x e. A ) -> R e. B )   &    |- ( ph -> F = ( x e. A |-> R ) )   &    |- ( ph -> G = ( y e. B |-> S ) )   &    |- ( y = R -> S = T )   =>    |- ( ph -> ( G o. F ) = ( x e. A |-> T ) )
Theorem	fmptcof 5822*	Version of fmptco 5821 where ph needn't be distinct from x. (Contributed by NM, 27-Dec-2014.)
|- ( ph -> A. x e. A R e. B )   &    |- ( ph -> F = ( x e. A |-> R ) )   &    |- ( ph -> G = ( y e. B |-> S ) )   &    |- ( y = R -> S = T )   =>    |- ( ph -> ( G o. F ) = ( x e. A |-> T ) )
Theorem	fmptcos 5823*	Composition of two functions expressed as mapping abstractions. (Contributed by NM, 22-May-2006.) (Revised by Mario Carneiro, 31-Aug-2015.)
|- ( ph -> A. x e. A R e. B )   &    |- ( ph -> F = ( x e. A |-> R ) )   &    |- ( ph -> G = ( y e. B |-> S ) )   =>    |- ( ph -> ( G o. F ) = ( x e. A |-> [_ R / y ]_ S ) )
Theorem	cofmpt 5824*	Express composition of a maps-to function with another function in a maps-to notation. (Contributed by Thierry Arnoux, 29-Jun-2017.)
|- ( ph -> F : C --> D )   &    |- ( ( ph /\ x e. A ) -> B e. C )   =>    |- ( ph -> ( F o. ( x e. A |-> B ) ) = ( x e. A |-> ( F ` B ) ) )
Theorem	fcompt 5825*	Express composition of two functions as a maps-to applying both in sequence. (Contributed by Stefan O'Rear, 5-Oct-2014.) (Proof shortened by Mario Carneiro, 27-Dec-2014.)
|- ( ( A : D --> E /\ B : C --> D ) -> ( A o. B ) = ( x e. C |-> ( A ` ( B ` x ) ) ) )
Theorem	fcoconst 5826	Composition with a constant function. (Contributed by Stefan O'Rear, 11-Mar-2015.)
|- ( ( F Fn X /\ Y e. X ) -> ( F o. ( I X. { Y } ) ) = ( I X. { ( F ` Y ) } ) )
Theorem	fsn 5827	A function maps a singleton to a singleton iff it is the singleton of an ordered pair. (Contributed by NM, 10-Dec-2003.)
|- A e. _V   &    |- B e. _V   =>    |- ( F : { A } --> { B } <-> F = { <. A , B >. } )
Theorem	fsng 5828	A function maps a singleton to a singleton iff it is the singleton of an ordered pair. (Contributed by NM, 26-Oct-2012.)
|- ( ( A e. C /\ B e. D ) -> ( F : { A } --> { B } <-> F = { <. A , B >. } ) )
Theorem	fsn2 5829	A function that maps a singleton to a class is the singleton of an ordered pair. (Contributed by NM, 19-May-2004.)
|- A e. _V   =>    |- ( F : { A } --> B <-> ( ( F ` A ) e. B /\ F = { <. A , ( F ` A ) >. } ) )
Theorem	fsn2g 5830	A function that maps a singleton to a class is the singleton of an ordered pair. (Contributed by Thierry Arnoux, 11-Jul-2020.)
|- ( A e. V -> ( F : { A } --> B <-> ( ( F ` A ) e. B /\ F = { <. A , ( F ` A ) >. } ) ) )
Theorem	xpsng 5831	The cross product of two singletons. (Contributed by Mario Carneiro, 30-Apr-2015.)
|- ( ( A e. V /\ B e. W ) -> ( { A } X. { B } ) = { <. A , B >. } )
Theorem	xpsn 5832	The cross product of two singletons. (Contributed by NM, 4-Nov-2006.)
|- A e. _V   &    |- B e. _V   =>    |- ( { A } X. { B } ) = { <. A , B >. }
Theorem	dfmpt 5833	Alternate definition for the maps-to notation df-mpt 4157 (although it requires that B be a set). (Contributed by NM, 24-Aug-2010.) (Revised by Mario Carneiro, 30-Dec-2016.)
|- B e. _V   =>    |- ( x e. A |-> B ) = U_ x e. A { <. x , B >. }
Theorem	fnasrn 5834	A function expressed as the range of another function. (Contributed by Mario Carneiro, 22-Jun-2013.) (Proof shortened by Mario Carneiro, 31-Aug-2015.)
|- B e. _V   =>    |- ( x e. A |-> B ) = ran ( x e. A |-> <. x , B >. )
Theorem	dfmptg 5835	Alternate definition for the maps-to notation df-mpt 4157 (which requires that B be a set). (Contributed by Jim Kingdon, 9-Jan-2019.)
|- ( A. x e. A B e. V -> ( x e. A |-> B ) = U_ x e. A { <. x , B >. } )
Theorem	fnasrng 5836	A function expressed as the range of another function. (Contributed by Jim Kingdon, 9-Jan-2019.)
|- ( A. x e. A B e. V -> ( x e. A |-> B ) = ran ( x e. A |-> <. x , B >. ) )
Theorem	funiun 5837*	A function is a union of singletons of ordered pairs indexed by its domain. (Contributed by AV, 18-Sep-2020.)
|- ( Fun F -> F = U_ x e. dom F { <. x , ( F ` x ) >. } )
Theorem	funopsn 5838*	If a function is an ordered pair then it is a singleton of an ordered pair. (Contributed by AV, 20-Sep-2020.) (Proof shortened by AV, 15-Jul-2021.) A function is a class of ordered pairs, so the fact that an ordered pair may sometimes be itself a function is an "accident" depending on the specific encoding of ordered pairs as classes (in set.mm, the Kuratowski encoding). A more meaningful statement is funsng 5383, as relsnopg 4836 is to relop 4886. (New usage is discouraged.)
|- X e. _V   &    |- Y e. _V   =>    |- ( ( Fun F /\ F = <. X , Y >. ) -> E. a ( X = { a } /\ F = { <. a , a >. } ) )
Theorem	funop 5839*	An ordered pair is a function iff it is a singleton of an ordered pair. (Contributed by AV, 20-Sep-2020.) A function is a class of ordered pairs, so the fact that an ordered pair may sometimes be itself a function is an "accident" depending on the specific encoding of ordered pairs as classes (in set.mm, the Kuratowski encoding). A more meaningful statement is funsng 5383, as relsnopg 4836 is to relop 4886. (New usage is discouraged.)
|- X e. _V   &    |- Y e. _V   =>    |- ( Fun <. X , Y >. <-> E. a ( X = { a } /\ <. X , Y >. = { <. a , a >. } ) )
Theorem	fncofn 5840	Composition of a function with domain and a function as a function with domain. Generalization of fnco 5447. (Contributed by AV, 17-Sep-2024.)
|- ( ( F Fn A /\ Fun G ) -> ( F o. G ) Fn ( `' G " A ) )
Theorem	fcof 5841	Composition of a function with domain and codomain and a function as a function with domain and codomain. Generalization of fco 5507. (Contributed by AV, 18-Sep-2024.)
|- ( ( F : A --> B /\ Fun G ) -> ( F o. G ) : ( `' G " A ) --> B )
Theorem	funopdmsn 5842	The domain of a function which is an ordered pair is a singleton. (Contributed by AV, 15-Nov-2021.) (Avoid depending on this detail.)
|- G = <. X , Y >.   &    |- X e. V   &    |- Y e. W   =>    |- ( ( Fun G /\ A e. dom G /\ B e. dom G ) -> A = B )
Theorem	ressnop0 5843	If A is not in C, then the restriction of a singleton of <. A , B >. to C is null. (Contributed by Scott Fenton, 15-Apr-2011.)
|- ( -. A e. C -> ( { <. A , B >. } |` C ) = (/) )
Theorem	fpr 5844	A function with a domain of two elements. (Contributed by Jeff Madsen, 20-Jun-2010.) (Proof shortened by Andrew Salmon, 22-Oct-2011.)
|- A e. _V   &    |- B e. _V   &    |- C e. _V   &    |- D e. _V   =>    |- ( A =/= B -> { <. A , C >. , <. B , D >. } : { A , B } --> { C , D } )
Theorem	fprg 5845	A function with a domain of two elements. (Contributed by FL, 2-Feb-2014.)
|- ( ( ( A e. E /\ B e. F ) /\ ( C e. G /\ D e. H ) /\ A =/= B ) -> { <. A , C >. , <. B , D >. } : { A , B } --> { C , D } )
Theorem	ftpg 5846	A function with a domain of three elements. (Contributed by Alexander van der Vekens, 4-Dec-2017.)
|- ( ( ( X e. U /\ Y e. V /\ Z e. W ) /\ ( A e. F /\ B e. G /\ C e. H ) /\ ( X =/= Y /\ X =/= Z /\ Y =/= Z ) ) -> { <. X , A >. , <. Y , B >. , <. Z , C >. } : { X , Y , Z } --> { A , B , C } )
Theorem	ftp 5847	A function with a domain of three elements. (Contributed by Stefan O'Rear, 17-Oct-2014.) (Proof shortened by Alexander van der Vekens, 23-Jan-2018.)
|- A e. _V   &    |- B e. _V   &    |- C e. _V   &    |- X e. _V   &    |- Y e. _V   &    |- Z e. _V   &    |- A =/= B   &    |- A =/= C   &    |- B =/= C   =>    |- { <. A , X >. , <. B , Y >. , <. C , Z >. } : { A , B , C } --> { X , Y , Z }
Theorem	fnressn 5848	A function restricted to a singleton. (Contributed by NM, 9-Oct-2004.)
|- ( ( F Fn A /\ B e. A ) -> ( F |` { B } ) = { <. B , ( F ` B ) >. } )
Theorem	fressnfv 5849	The value of a function restricted to a singleton. (Contributed by NM, 9-Oct-2004.)
|- ( ( F Fn A /\ B e. A ) -> ( ( F |` { B } ) : { B } --> C <-> ( F ` B ) e. C ) )
Theorem	fvconst 5850	The value of a constant function. (Contributed by NM, 30-May-1999.)
|- ( ( F : A --> { B } /\ C e. A ) -> ( F ` C ) = B )
Theorem	fmptsn 5851*	Express a singleton function in maps-to notation. (Contributed by NM, 6-Jun-2006.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) (Revised by Stefan O'Rear, 28-Feb-2015.)
|- ( ( A e. V /\ B e. W ) -> { <. A , B >. } = ( x e. { A } |-> B ) )
Theorem	fmptap 5852*	Append an additional value to a function. (Contributed by NM, 6-Jun-2006.) (Revised by Mario Carneiro, 31-Aug-2015.)
|- A e. _V   &    |- B e. _V   &    |- ( R u. { A } ) = S   &    |- ( x = A -> C = B )   =>    |- ( ( x e. R |-> C ) u. { <. A , B >. } ) = ( x e. S |-> C )
Theorem	fmptapd 5853*	Append an additional value to a function. (Contributed by Thierry Arnoux, 3-Jan-2017.)
|- ( ph -> A e. _V )   &    |- ( ph -> B e. _V )   &    |- ( ph -> ( R u. { A } ) = S )   &    |- ( ( ph /\ x = A ) -> C = B )   =>    |- ( ph -> ( ( x e. R |-> C ) u. { <. A , B >. } ) = ( x e. S |-> C ) )
Theorem	fmptpr 5854*	Express a pair function in maps-to notation. (Contributed by Thierry Arnoux, 3-Jan-2017.)
|- ( ph -> A e. V )   &    |- ( ph -> B e. W )   &    |- ( ph -> C e. X )   &    |- ( ph -> D e. Y )   &    |- ( ( ph /\ x = A ) -> E = C )   &    |- ( ( ph /\ x = B ) -> E = D )   =>    |- ( ph -> { <. A , C >. , <. B , D >. } = ( x e. { A , B } |-> E ) )
Theorem	fvresi 5855	The value of a restricted identity function. (Contributed by NM, 19-May-2004.)
|- ( B e. A -> ( ( _I |` A ) ` B ) = B )
Theorem	fvunsng 5856	Remove an ordered pair not participating in a function value. (Contributed by Jim Kingdon, 7-Jan-2019.)
|- ( ( D e. V /\ B =/= D ) -> ( ( A u. { <. B , C >. } ) ` D ) = ( A ` D ) )
Theorem	fvsn 5857	The value of a singleton of an ordered pair is the second member. (Contributed by NM, 12-Aug-1994.)
|- A e. _V   &    |- B e. _V   =>    |- ( { <. A , B >. } ` A ) = B
Theorem	fvsng 5858	The value of a singleton of an ordered pair is the second member. (Contributed by NM, 26-Oct-2012.)
|- ( ( A e. V /\ B e. W ) -> ( { <. A , B >. } ` A ) = B )
Theorem	fvsnun1 5859	The value of a function with one of its ordered pairs replaced, at the replaced ordered pair. See also fvsnun2 5860. (Contributed by NM, 23-Sep-2007.)
|- A e. _V   &    |- B e. _V   &    |- G = ( { <. A , B >. } u. ( F |` ( C \ { A } ) ) )   =>    |- ( G ` A ) = B
Theorem	fvsnun2 5860	The value of a function with one of its ordered pairs replaced, at arguments other than the replaced one. See also fvsnun1 5859. (Contributed by NM, 23-Sep-2007.)
|- A e. _V   &    |- B e. _V   &    |- G = ( { <. A , B >. } u. ( F |` ( C \ { A } ) ) )   =>    |- ( D e. ( C \ { A } ) -> ( G ` D ) = ( F ` D ) )
Theorem	fnsnsplitss 5861	Split a function into a single point and all the rest. (Contributed by Stefan O'Rear, 27-Feb-2015.) (Revised by Jim Kingdon, 20-Jan-2023.)
|- ( ( F Fn A /\ X e. A ) -> ( ( F |` ( A \ { X } ) ) u. { <. X , ( F ` X ) >. } ) C_ F )
Theorem	fsnunf 5862	Adjoining a point to a function gives a function. (Contributed by Stefan O'Rear, 28-Feb-2015.)
|- ( ( F : S --> T /\ ( X e. V /\ -. X e. S ) /\ Y e. T ) -> ( F u. { <. X , Y >. } ) : ( S u. { X } ) --> T )
Theorem	fsnunfv 5863	Recover the added point from a point-added function. (Contributed by Stefan O'Rear, 28-Feb-2015.) (Revised by NM, 18-May-2017.)
|- ( ( X e. V /\ Y e. W /\ -. X e. dom F ) -> ( ( F u. { <. X , Y >. } ) ` X ) = Y )
Theorem	fsnunres 5864	Recover the original function from a point-added function. (Contributed by Stefan O'Rear, 28-Feb-2015.)
|- ( ( F Fn S /\ -. X e. S ) -> ( ( F u. { <. X , Y >. } ) |` S ) = F )
Theorem	funresdfunsnss 5865	Restricting a function to a domain without one element of the domain of the function, and adding a pair of this element and the function value of the element results in a subset of the function itself. (Contributed by AV, 2-Dec-2018.) (Revised by Jim Kingdon, 21-Jan-2023.)
|- ( ( Fun F /\ X e. dom F ) -> ( ( F |` ( _V \ { X } ) ) u. { <. X , ( F ` X ) >. } ) C_ F )
Theorem	fvpr1 5866	The value of a function with a domain of two elements. (Contributed by Jeff Madsen, 20-Jun-2010.)
|- A e. _V   &    |- C e. _V   =>    |- ( A =/= B -> ( { <. A , C >. , <. B , D >. } ` A ) = C )
Theorem	fvpr2 5867	The value of a function with a domain of two elements. (Contributed by Jeff Madsen, 20-Jun-2010.)
|- B e. _V   &    |- D e. _V   =>    |- ( A =/= B -> ( { <. A , C >. , <. B , D >. } ` B ) = D )
Theorem	fvpr1g 5868	The value of a function with a domain of (at most) two elements. (Contributed by Alexander van der Vekens, 3-Dec-2017.)
|- ( ( A e. V /\ C e. W /\ A =/= B ) -> ( { <. A , C >. , <. B , D >. } ` A ) = C )
Theorem	fvpr2g 5869	The value of a function with a domain of (at most) two elements. (Contributed by Alexander van der Vekens, 3-Dec-2017.)
|- ( ( B e. V /\ D e. W /\ A =/= B ) -> ( { <. A , C >. , <. B , D >. } ` B ) = D )
Theorem	fvtp1g 5870	The value of a function with a domain of (at most) three elements. (Contributed by Alexander van der Vekens, 4-Dec-2017.)
|- ( ( ( A e. V /\ D e. W ) /\ ( A =/= B /\ A =/= C ) ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` A ) = D )
Theorem	fvtp2g 5871	The value of a function with a domain of (at most) three elements. (Contributed by Alexander van der Vekens, 4-Dec-2017.)
|- ( ( ( B e. V /\ E e. W ) /\ ( A =/= B /\ B =/= C ) ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` B ) = E )
Theorem	fvtp3g 5872	The value of a function with a domain of (at most) three elements. (Contributed by Alexander van der Vekens, 4-Dec-2017.)
|- ( ( ( C e. V /\ F e. W ) /\ ( A =/= C /\ B =/= C ) ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` C ) = F )
Theorem	fvtp1 5873	The first value of a function with a domain of three elements. (Contributed by NM, 14-Sep-2011.)
|- A e. _V   &    |- D e. _V   =>    |- ( ( A =/= B /\ A =/= C ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` A ) = D )
Theorem	fvtp2 5874	The second value of a function with a domain of three elements. (Contributed by NM, 14-Sep-2011.)
|- B e. _V   &    |- E e. _V   =>    |- ( ( A =/= B /\ B =/= C ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` B ) = E )
Theorem	fvtp3 5875	The third value of a function with a domain of three elements. (Contributed by NM, 14-Sep-2011.)
|- C e. _V   &    |- F e. _V   =>    |- ( ( A =/= C /\ B =/= C ) -> ( { <. A , D >. , <. B , E >. , <. C , F >. } ` C ) = F )
Theorem	fvconst2g 5876	The value of a constant function. (Contributed by NM, 20-Aug-2005.)
|- ( ( B e. D /\ C e. A ) -> ( ( A X. { B } ) ` C ) = B )
Theorem	fconst2g 5877	A constant function expressed as a cross product. (Contributed by NM, 27-Nov-2007.)
|- ( B e. C -> ( F : A --> { B } <-> F = ( A X. { B } ) ) )
Theorem	fvconst2 5878	The value of a constant function. (Contributed by NM, 16-Apr-2005.)
|- B e. _V   =>    |- ( C e. A -> ( ( A X. { B } ) ` C ) = B )
Theorem	fconst2 5879	A constant function expressed as a cross product. (Contributed by NM, 20-Aug-1999.)
|- B e. _V   =>    |- ( F : A --> { B } <-> F = ( A X. { B } ) )
Theorem	fconstfvm 5880*	A constant function expressed in terms of its functionality, domain, and value. See also fconst2 5879. (Contributed by Jim Kingdon, 8-Jan-2019.)
|- ( E. y y e. A -> ( F : A --> { B } <-> ( F Fn A /\ A. x e. A ( F ` x ) = B ) ) )
Theorem	fconst3m 5881*	Two ways to express a constant function. (Contributed by Jim Kingdon, 8-Jan-2019.)
|- ( E. x x e. A -> ( F : A --> { B } <-> ( F Fn A /\ A C_ ( `' F " { B } ) ) ) )
Theorem	fconst4m 5882*	Two ways to express a constant function. (Contributed by NM, 8-Mar-2007.)
|- ( E. x x e. A -> ( F : A --> { B } <-> ( F Fn A /\ ( `' F " { B } ) = A ) ) )
Theorem	resfunexg 5883	The restriction of a function to a set exists. Compare Proposition 6.17 of [TakeutiZaring] p. 28. (Contributed by NM, 7-Apr-1995.) (Revised by Mario Carneiro, 22-Jun-2013.)
|- ( ( Fun A /\ B e. C ) -> ( A |` B ) e. _V )
Theorem	fnex 5884	If the domain of a function is a set, the function is a set. Theorem 6.16(1) of [TakeutiZaring] p. 28. This theorem is derived using the Axiom of Replacement in the form of resfunexg 5883. (Contributed by NM, 14-Aug-1994.) (Proof shortened by Andrew Salmon, 17-Sep-2011.)
|- ( ( F Fn A /\ A e. B ) -> F e. _V )
Theorem	fndmexb 5885	The domain of a function is a set iff the function is a set. (Contributed by AV, 8-Aug-2024.)
|- ( F Fn A -> ( A e. _V <-> F e. _V ) )
Theorem	fdmexb 5886	The domain of a function is a set iff the function is a set. (Contributed by AV, 8-Aug-2024.)
|- ( F : A --> B -> ( A e. _V <-> F e. _V ) )
Theorem	funex 5887	If the domain of a function exists, so does the function. Part of Theorem 4.15(v) of [Monk1] p. 46. This theorem is derived using the Axiom of Replacement in the form of fnex 5884. (Note: Any resemblance between F.U.N.E.X. and "Have You Any Eggs" is purely a coincidence originated by Swedish chefs.) (Contributed by NM, 11-Nov-1995.)
|- ( ( Fun F /\ dom F e. B ) -> F e. _V )
Theorem	opabex 5888*	Existence of a function expressed as class of ordered pairs. (Contributed by NM, 21-Jul-1996.)
|- A e. _V   &    |- ( x e. A -> E* y ph )   =>    |- { <. x , y >. | ( x e. A /\ ph ) } e. _V
Theorem	mptexg 5889*	If the domain of a function given by maps-to notation is a set, the function is a set. (Contributed by FL, 6-Jun-2011.) (Revised by Mario Carneiro, 31-Aug-2015.)
|- ( A e. V -> ( x e. A |-> B ) e. _V )
Theorem	mptex 5890*	If the domain of a function given by maps-to notation is a set, the function is a set. (Contributed by NM, 22-Apr-2005.) (Revised by Mario Carneiro, 20-Dec-2013.)
|- A e. _V   =>    |- ( x e. A |-> B ) e. _V
Theorem	mptexd 5891*	If the domain of a function given by maps-to notation is a set, the function is a set. Deduction version of mptexg 5889. (Contributed by Glauco Siliprandi, 24-Dec-2020.)
|- ( ph -> A e. V )   =>    |- ( ph -> ( x e. A |-> B ) e. _V )
Theorem	mptrabex 5892*	If the domain of a function given by maps-to notation is a class abstraction based on a set, the function is a set. (Contributed by AV, 16-Jul-2019.) (Revised by AV, 26-Mar-2021.)
|- A e. _V   =>    |- ( x e. { y e. A | ph } |-> B ) e. _V
Theorem	fex 5893	If the domain of a mapping is a set, the function is a set. (Contributed by NM, 3-Oct-1999.)
|- ( ( F : A --> B /\ A e. C ) -> F e. _V )
Theorem	fexd 5894	If the domain of a mapping is a set, the function is a set. (Contributed by Glauco Siliprandi, 26-Jun-2021.)
|- ( ph -> F : A --> B )   &    |- ( ph -> A e. C )   =>    |- ( ph -> F e. _V )
Theorem	eufnfv 5895*	A function is uniquely determined by its values. (Contributed by NM, 31-Aug-2011.)
|- A e. _V   &    |- B e. _V   =>    |- E! f ( f Fn A /\ A. x e. A ( f ` x ) = B )
Theorem	funfvima 5896	A function's value in a preimage belongs to the image. (Contributed by NM, 23-Sep-2003.)
|- ( ( Fun F /\ B e. dom F ) -> ( B e. A -> ( F ` B ) e. ( F " A ) ) )
Theorem	funfvima2 5897	A function's value in an included preimage belongs to the image. (Contributed by NM, 3-Feb-1997.)
|- ( ( Fun F /\ A C_ dom F ) -> ( B e. A -> ( F ` B ) e. ( F " A ) ) )
Theorem	funfvima3 5898	A class including a function contains the function's value in the image of the singleton of the argument. (Contributed by NM, 23-Mar-2004.)
|- ( ( Fun F /\ F C_ G ) -> ( A e. dom F -> ( F ` A ) e. ( G " { A } ) ) )
Theorem	fnfvima 5899	The function value of an operand in a set is contained in the image of that set, using the Fn abbreviation. (Contributed by Stefan O'Rear, 10-Mar-2015.)
|- ( ( F Fn A /\ S C_ A /\ X e. S ) -> ( F ` X ) e. ( F " S ) )
Theorem	fnfvimad 5900	A function's value belongs to the image. (Contributed by Glauco Siliprandi, 23-Oct-2021.)
|- ( ph -> F Fn A )   &    |- ( ph -> B e. A )   &    |- ( ph -> B e. C )   =>    |- ( ph -> ( F ` B ) e. ( F " C ) )