mmtheorems36 - Metamath Proof Explorer

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Statement List for Metamath Proof Explorer - 3501-3600 - Page 36 of 107

Type	Label	Description
Statement
Theorem	imaco 3501	Image of the composition of two classes. (Contributed by Jason Orendorff, 12-Dec-2006.)
|- ((A o. B)"C) = (A"(B"C))
Theorem	rnco 3502	The range of the composition of two classes.
|- ran ( A o. B) = ran ( A |` ran B)
Theorem	rnco2 3503	The range of the composition of two classes.
|- ran ( A o. B) = (A"ran B)
Theorem	dmco2 3504	The domain of a composition. Exercise 27 of [Enderton] p. 53.
|- dom ( A o. B) = (`'B"dom A)
Theorem	cocnvcnv1 3505	A composition is not affected by a double converse of its first argument.
|- (`'`'A o. B) = (A o. B)
Theorem	cocnvcnv2 3506	A composition is not affected by a double converse of its second argument.
|- (A o. `'`'B) = (A o. B)
Theorem	cores2 3507	Absorption of a reverse (preimage) restriction of the second member of a class composition.
|- (dom A (_ C -> (A o. `'(`'B |` C)) = (A o. B))
Theorem	co02 3508	Composition with the empty set. Theorem 20 of [Suppes] p. 63.
|- (A o. (/)) = (/)
Theorem	co01 3509	Composition with the empty set.
|- ((/) o. A) = (/)
Theorem	coi1 3510	Composition with the identity relation. Part of Theorem 3.7(i) of [Monk1] p. 36.
|- (Rel A -> (A o. I) = A)
Theorem	coi2 3511	Composition with the identity relation. Part of Theorem 3.7(i) of [Monk1] p. 36.
|- (Rel A -> (I o. A) = A)
Theorem	coass 3512	Associative law for class composition. Theorem 27 of [Suppes] p. 64. Also Exercise 21 of [Enderton] p. 53. Interestingly, this law holds for any classes whatsoever, not just functions or even relations.
|- ((A o. B) o. C) = (A o. (B o. C))
Theorem	relssdr 3513	A relation is included in the cross product of its domain and range. Exercise 4.12(t) of [Mendelson] p. 235.
|- (Rel A -> A (_ (dom A X. ran A))
Theorem	unielrel 3514	The membership relation for a relation is inherited by class union.
|- ((Rel R /\ A e. R) -> U.A e. U.R)
Theorem	relfld 3515	The double union of a relation is its field.
|- (Rel R -> U.U.R = (dom R u. ran R))
Theorem	unidmrnOLD 3516	The double union of the universal restriction of a class.
|- U.U.(A |` V) = (dom A u. ran A)
Theorem	unidmrn 3517	The double union of the converse of a class is its field.
|- U.U.`'A = (dom A u. ran A)
Theorem	unixp 3518	The double class union of a non-empty cross product is the union of it members.
|- ((A X. B) =/= (/) -> U.U.(A X. B) = (A u. B))
Theorem	unixp0 3519	A cross product is empty iff its union is empty.
|- ((A X. B) = (/) <-> U.(A X. B) = (/))
Theorem	cnvexg 3520	The converse of a set is a set. Corollary 6.8(1) of [TakeutiZaring] p. 26.
|- (A e. B -> `'A e. V)
Theorem	cnvex 3521	The converse of a set is a set. Corollary 6.8(1) of [TakeutiZaring] p. 26.
|- A e. V   =>   |- `'A e. V
Theorem	relcnvexb 3522	A relation is a set iff its converse is a set. (Contributed by FL, 3-Mar-2007.)
|- (Rel R -> (R e. V <-> `'R e. V))
Theorem	cnvpo 3523	The converse of a partial order relation is a partial order relation.
|- (R Po A <-> `'R Po A)
Theorem	cnvso 3524	The converse of a strict order relation is a strict order relation.
|- (R Or A <-> `'R Or A)
Theorem	coexg 3525	The composition of two sets is a set.
|- ((A e. C /\ B e. D) -> (A o. B) e. V)
Theorem	coex 3526	The composition of two sets is a set.
|- A e. V   &   |- B e. V   =>   |- (A o. B) e. V
Theorem	dffun2 3527	Alternate definition of a function.
|- (Fun A <-> (Rel A /\ A.xA.yA.z((xAy /\ xAz) -> y = z)))
Theorem	dffun3 3528	Alternate definition of function.
|- (Fun A <-> (Rel A /\ A.xE.zA.y(xAy -> y = z)))
Theorem	dffun4 3529	Alternate definition of a function. Definition 6.4(4) of [TakeutiZaring] p. 24.
|- (Fun A <-> (Rel A /\ A.xA.yA.z((<.x, y>. e. A /\ <.x, z>. e. A) -> y = z)))
Theorem	dffun5 3530	Alternate definition of function.
|- (Fun A <-> (Rel A /\ A.xE.zA.y(<.x, y>. e. A -> y = z)))
Theorem	dffunmof 3531	Definition of function, using bound-variable hypotheses instead of distinct variable conditions.
|- (z e. A -> A.x z e. A)   &   |- (z e. A -> A.y z e. A)   =>   |- (Fun A <-> (Rel A /\ A.xE*y xAy))
Theorem	dffunmo 3532	Alternate definition of a function using "at most one" notation.
|- (Fun A <-> (Rel A /\ A.xE*y xAy))
Theorem	funmo 3533	A function has at most one value for each argument.
|- (Fun A -> E*y xAy)
Theorem	funrel 3534	A function is a relation.
|- (Fun A -> Rel A)
Theorem	funss 3535	Subclass theorem for function predicate.
|- (A (_ B -> (Fun B -> Fun A))
Theorem	funeq 3536	Equality theorem for function predicate.
|- (A = B -> (Fun A <-> Fun B))
Theorem	hbfun 3537	Bound-variable hypothesis builder for a function.
|- (y e. F -> A.x y e. F)   =>   |- (Fun F -> A.xFun F)
Theorem	funeu 3538	There is exactly one value of a function.
|- ((Fun F /\ xFy) -> E!y xFy)
Theorem	funeu2 3539	There is exactly one value of a function.
|- ((Fun F /\ <.x, y>. e. F) -> E!y<.x, y>. e. F)
Theorem	dffun6 3540	Alternate definition of a function. One possibility for the definition of a function in [Enderton] p. 42. (Enderton's definition is ambiguous because "there is only one" could mean either "there is at most one" or "there is exactly one." However, dffun7 3541 shows that it doesn't matter which meaning we pick.)
|- (Fun A <-> (Rel A /\ A.x e. dom AE*y xAy))
Theorem	dffun7 3541	Alternate definition of a function. One possibility for the definition of a function in [Enderton] p. 42. Compare dffun6 3540.
|- (Fun A <-> (Rel A /\ A.x e. dom AE!y xAy))
Theorem	dffun8 3542	Alternate definition of a function.
|- (Fun A <-> (Rel A /\ A.x e. dom AE*y(y e. ran A /\ xAy)))
Theorem	funfn 3543	An equivalence for the function predicate.
|- (Fun A <-> A Fn dom A)
Theorem	funsn 3544	A singleton of an ordered pair is a function. Theorem 10.5 of [Quine] p. 65.
|- A e. V   &   |- B e. V   =>   |- Fun {<.A, B>.}
Theorem	fun0 3545	The empty set is a function. Theorem 10.3 of [Quine] p. 65.
|- Fun (/)
Theorem	funi 3546	The identity relation is a function. Part of Theorem 10.4 of [Quine] p. 65.
|- Fun I
Theorem	nfunv 3547	The universe is not a function. (Contributed by Raph Levien, 27-Jan-2004.)
|- -. Fun V
Theorem	funop 3548	A Kuratowski ordered pair is a function only if its components are equal.
|- A e. V   &   |- B e. V   =>   |- (Fun <.A, B>. -> A = B)
Theorem	funopg 3549	A Kuratowski ordered pair is a function only if its components are equal.
|- ((B e. C /\ Fun <.A, B>.) -> A = B)
Theorem	funopab 3550	A class of ordered pairs is a function when there is at most one second member for each pair.
|- (Fun {<.x, y>. | ph} <-> A.xE*yph)
Theorem	funopabeq 3551	A class of ordered pairs of values is a function.
|- Fun {<.x, y>. | y = A}
Theorem	funco 3552	The composition of two functions is a function. Exercise 29 of [TakeutiZaring] p. 25.
|- ((Fun F /\ Fun G) -> Fun (F o. G))
Theorem	funres 3553	A restriction of a function is a function. Compare Exercise 18 of [TakeutiZaring] p. 25.
|- (Fun F -> Fun (F |` A))
Theorem	funssres 3554	The restriction of a function to the domain of a subclass equals the subclass.
|- ((Fun F /\ G (_ F) -> (F |` dom G) = G)
Theorem	fun2ssres 3555	Equality of restrictions of a function and a subclass.
|- ((Fun F /\ G (_ F /\ A (_ dom G) -> (F |` A) = (G |` A))
Theorem	funun 3556	The union of functions with disjoint domains is a function. Theorem 4.6 of [Monk1] p. 43.
|- (((Fun F /\ Fun G) /\ (dom F i^i dom G) = (/)) -> Fun (F u. G))
Theorem	funcnvcnv 3557	The double converse of a function is a function.
|- (Fun A -> Fun `'`'A)
Theorem	funcnv2 3558	A simpler equivalence for single-rooted (see funcnv 3559).
|- (Fun `'A <-> A.yE*x xAy)
Theorem	funcnv 3559	The converse of a class is a function iff the class is single-rooted, which means that for any y in the range of A there is at most one x such that xAy. Definition of single-rooted in [Enderton] p. 43. See funcnv2 3558 for a simpler version.
|- (Fun `'A <-> A.y e. ran AE*x xAy)
Theorem	funcnv3 3560	A condition showing a class is single-rooted. (See funcnv 3559).
|- (Fun `'A <-> A.y e. ran AE!x e. dom A xAy)
Theorem	fun2cnv 3561	The double converse of a class is a function iff the class is single-valued. Each side is equivalent to Definition 6.4(2) of [TakeutiZaring] p. 23, who use the notation "Un(A)" for single-valued. Note that A is not necessarily a function.
|- (Fun `'`'A <-> A.xE*y xAy)
Theorem	svrelfun 3562	A single-valued relation is a function. (See fun2cnv 3561 for "single-valued.") Definition 6.4(4) of [TakeutiZaring] p. 24.
|- (Fun A <-> (Rel A /\ Fun `'`'A))
Theorem	fncnv 3563	Single-rootedness (see funcnv 3559) of a class cut down by a cross product.
|- (`'(R i^i (A X. B)) Fn B <-> A.y e. B E!x e. A xRy)
Theorem	fun11 3564	Two ways of stating that A is one-to-one (but not necessarily a function). Each side is equivalent to Definition 6.4(3) of [TakeutiZaring] p. 24, who use the notation "Un2 (A)" for one-to-one (but not necessarily a function).
|- ((Fun `'`'A /\ Fun `'A) <-> A.xA.yA.zA.w((xAy /\ zAw) -> (x = z <-> y = w)))
Theorem	fununi 3565	The union of a chain (with respect to inclusion) of functions is a function.
|- (A.f e. A (Fun f /\ A.g e. A (f (_ g \/ g (_ f)) -> Fun U.A)
Theorem	funcnvuni 3566	The union of a chain (with respect to inclusion) of single-rooted sets is single-rooted. (See funcnv 3559 for "single-rooted" definition.)
|- (A.f e. A (Fun `'f /\ A.g e. A (f (_ g \/ g (_ f)) -> Fun `'U.A)
Theorem	fun11uni 3567	The union of a chain (with respect to inclusion) of one-to-one functions is a one-to-one function.
|- (A.f e. A ((Fun f /\ Fun `'f) /\ A.g e. A (f (_ g \/ g (_ f)) -> (Fun U.A /\ Fun `'U.A))
Theorem	funin 3568	The intersection with a function is a function. Exercise 14(a) of [Enderton] p. 53.
|- (Fun F -> Fun (F i^i G))
Theorem	funres11 3569	The restriction of a one-to-one function is one-to-one.
|- (Fun `'F -> Fun `'(F |` A))
Theorem	funcnvres 3570	The converse of a restricted function.
|- (Fun `'F -> `'(F |` A) = (`'F |` (F"A)))
Theorem	cnvresid 3571	Converse of a restricted identity function. (Contributed by FL, 4-Mar-2007.)
|- `'(I |` A) = (I |` A)
Theorem	funcnvres2 3572	The converse of a restriction of the converse of a function equals the function restricted to the image of its converse.
|- (Fun F -> `'(`'F |` A) = (F |` (`'F"A)))
Theorem	funimacnv 3573	The image of the pre-image of a function.
|- (Fun F -> (F"(`'F"A)) = (A i^i ran F))
Theorem	funimass1 3574	A kind of contraposition law that infers a subclass of an image from a pre-image subclass.
|- ((Fun F /\ A (_ ran F) -> ((`'F"A) (_ B -> A (_ (F"B)))
Theorem	funimass2 3575	A kind of contraposition law that infers an image subclass from a subclass of a pre-image.
|- ((Fun F /\ A (_ (`'F"B)) -> (F"A) (_ B)
Theorem	imadif 3576	The image of a difference is the difference of images.
|-