P. 150 of Theorem List - Intuitionistic Logic Explorer

Theorem List for Intuitionistic Logic Explorer - 14901-15000   *Has distinct variable group(s)

Type	Label	Description
Statement
9.2.5  Continuity in metric spaces
Theorem	metcnp3 14901*	Two ways to express that F is continuous at P for metric spaces. Proposition 14-4.2 of [Gleason] p. 240. (Contributed by NM, 17-May-2007.) (Revised by Mario Carneiro, 28-Aug-2015.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) /\ P e. X ) -> ( F e. ( ( J CnP K ) ` P ) <-> ( F : X --> Y /\ A. y e. RR+ E. z e. RR+ ( F " ( P ( ball ` C ) z ) ) C_ ( ( F ` P ) ( ball ` D ) y ) ) ) )
Theorem	metcnp 14902*	Two ways to say a mapping from metric C to metric D is continuous at point P. (Contributed by NM, 11-May-2007.) (Revised by Mario Carneiro, 28-Aug-2015.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) /\ P e. X ) -> ( F e. ( ( J CnP K ) ` P ) <-> ( F : X --> Y /\ A. y e. RR+ E. z e. RR+ A. w e. X ( ( P C w ) < z -> ( ( F ` P ) D ( F ` w ) ) < y ) ) ) )
Theorem	metcnp2 14903*	Two ways to say a mapping from metric C to metric D is continuous at point P. The distance arguments are swapped compared to metcnp 14902 (and Munkres' metcn 14904) for compatibility with df-lm 14580. Definition 1.3-3 of [Kreyszig] p. 20. (Contributed by NM, 4-Jun-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) /\ P e. X ) -> ( F e. ( ( J CnP K ) ` P ) <-> ( F : X --> Y /\ A. y e. RR+ E. z e. RR+ A. w e. X ( ( w C P ) < z -> ( ( F ` w ) D ( F ` P ) ) < y ) ) ) )
Theorem	metcn 14904*	Two ways to say a mapping from metric C to metric D is continuous. Theorem 10.1 of [Munkres] p. 127. The second biconditional argument says that for every positive "epsilon" y there is a positive "delta" z such that a distance less than delta in C maps to a distance less than epsilon in D. (Contributed by NM, 15-May-2007.) (Revised by Mario Carneiro, 28-Aug-2015.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) ) -> ( F e. ( J Cn K ) <-> ( F : X --> Y /\ A. x e. X A. y e. RR+ E. z e. RR+ A. w e. X ( ( x C w ) < z -> ( ( F ` x ) D ( F ` w ) ) < y ) ) ) )
Theorem	metcnpi 14905*	Epsilon-delta property of a continuous metric space function, with function arguments as in metcnp 14902. (Contributed by NM, 17-Dec-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) ) /\ ( F e. ( ( J CnP K ) ` P ) /\ A e. RR+ ) ) -> E. x e. RR+ A. y e. X ( ( P C y ) < x -> ( ( F ` P ) D ( F ` y ) ) < A ) )
Theorem	metcnpi2 14906*	Epsilon-delta property of a continuous metric space function, with swapped distance function arguments as in metcnp2 14903. (Contributed by NM, 16-Dec-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) ) /\ ( F e. ( ( J CnP K ) ` P ) /\ A e. RR+ ) ) -> E. x e. RR+ A. y e. X ( ( y C P ) < x -> ( ( F ` y ) D ( F ` P ) ) < A ) )
Theorem	metcnpi3 14907*	Epsilon-delta property of a metric space function continuous at P. A variation of metcnpi2 14906 with non-strict ordering. (Contributed by NM, 16-Dec-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) ) /\ ( F e. ( ( J CnP K ) ` P ) /\ A e. RR+ ) ) -> E. x e. RR+ A. y e. X ( ( y C P ) <_ x -> ( ( F ` y ) D ( F ` P ) ) <_ A ) )
Theorem	txmetcnp 14908*	Continuity of a binary operation on metric spaces. (Contributed by Mario Carneiro, 2-Sep-2015.) (Revised by Jim Kingdon, 22-Oct-2023.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   &    |- L = ( MetOpen ` E )   =>    |- ( ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) /\ E e. ( *Met ` Z ) ) /\ ( A e. X /\ B e. Y ) ) -> ( F e. ( ( ( J tX K ) CnP L ) ` <. A , B >. ) <-> ( F : ( X X. Y ) --> Z /\ A. z e. RR+ E. w e. RR+ A. u e. X A. v e. Y ( ( ( A C u ) < w /\ ( B D v ) < w ) -> ( ( A F B ) E ( u F v ) ) < z ) ) ) )
Theorem	txmetcn 14909*	Continuity of a binary operation on metric spaces. (Contributed by Mario Carneiro, 2-Sep-2015.)
|- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   &    |- L = ( MetOpen ` E )   =>    |- ( ( C e. ( *Met ` X ) /\ D e. ( *Met ` Y ) /\ E e. ( *Met ` Z ) ) -> ( F e. ( ( J tX K ) Cn L ) <-> ( F : ( X X. Y ) --> Z /\ A. x e. X A. y e. Y A. z e. RR+ E. w e. RR+ A. u e. X A. v e. Y ( ( ( x C u ) < w /\ ( y D v ) < w ) -> ( ( x F y ) E ( u F v ) ) < z ) ) ) )
Theorem	metcnpd 14910*	Two ways to say a mapping from metric C to metric D is continuous at point P. (Contributed by Jim Kingdon, 14-Jun-2023.)
|- ( ph -> J = ( MetOpen ` C ) )   &    |- ( ph -> K = ( MetOpen ` D ) )   &    |- ( ph -> C e. ( *Met ` X ) )   &    |- ( ph -> D e. ( *Met ` Y ) )   &    |- ( ph -> P e. X )   =>    |- ( ph -> ( F e. ( ( J CnP K ) ` P ) <-> ( F : X --> Y /\ A. y e. RR+ E. z e. RR+ A. w e. X ( ( P C w ) < z -> ( ( F ` P ) D ( F ` w ) ) < y ) ) ) )
9.2.6  Topology on the reals
Theorem	qtopbasss 14911*	The set of open intervals with endpoints in a subset forms a basis for a topology. (Contributed by Mario Carneiro, 17-Jun-2014.) (Revised by Jim Kingdon, 22-May-2023.)
|- S C_ RR*   &    |- ( ( x e. S /\ y e. S ) -> sup ( { x , y } , RR* , < ) e. S )   &    |- ( ( x e. S /\ y e. S ) -> inf ( { x , y } , RR* , < ) e. S )   =>    |- ( (,) " ( S X. S ) ) e. TopBases
Theorem	qtopbas 14912	The set of open intervals with rational endpoints forms a basis for a topology. (Contributed by NM, 8-Mar-2007.)
|- ( (,) " ( QQ X. QQ ) ) e. TopBases
Theorem	retopbas 14913	A basis for the standard topology on the reals. (Contributed by NM, 6-Feb-2007.) (Proof shortened by Mario Carneiro, 17-Jun-2014.)
|- ran (,) e. TopBases
Theorem	retop 14914	The standard topology on the reals. (Contributed by FL, 4-Jun-2007.)
|- ( topGen ` ran (,) ) e. Top
Theorem	uniretop 14915	The underlying set of the standard topology on the reals is the reals. (Contributed by FL, 4-Jun-2007.)
|- RR = U. ( topGen ` ran (,) )
Theorem	retopon 14916	The standard topology on the reals is a topology on the reals. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- ( topGen ` ran (,) ) e. (TopOn ` RR )
Theorem	retps 14917	The standard topological space on the reals. (Contributed by NM, 19-Oct-2012.)
|- K = { <. ( Base ` ndx ) , RR >. , <. (TopSet ` ndx ) , ( topGen ` ran (,) ) >. }   =>    |- K e. TopSp
Theorem	iooretopg 14918	Open intervals are open sets of the standard topology on the reals . (Contributed by FL, 18-Jun-2007.) (Revised by Jim Kingdon, 23-May-2023.)
|- ( ( A e. RR* /\ B e. RR* ) -> ( A (,) B ) e. ( topGen ` ran (,) ) )
Theorem	cnmetdval 14919	Value of the distance function of the metric space of complex numbers. (Contributed by NM, 9-Dec-2006.) (Revised by Mario Carneiro, 27-Dec-2014.)
|- D = ( abs o. - )   =>    |- ( ( A e. CC /\ B e. CC ) -> ( A D B ) = ( abs ` ( A - B ) ) )
Theorem	cnmet 14920	The absolute value metric determines a metric space on the complex numbers. This theorem provides a link between complex numbers and metrics spaces, making metric space theorems available for use with complex numbers. (Contributed by FL, 9-Oct-2006.)
|- ( abs o. - ) e. ( Met ` CC )
Theorem	cnxmet 14921	The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- ( abs o. - ) e. ( *Met ` CC )
Theorem	cntoptopon 14922	The topology of the complex numbers is a topology. (Contributed by Jim Kingdon, 6-Jun-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- J e. (TopOn ` CC )
Theorem	cntoptop 14923	The topology of the complex numbers is a topology. (Contributed by Jim Kingdon, 6-Jun-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- J e. Top
Theorem	cnbl0 14924	Two ways to write the open ball centered at zero. (Contributed by Mario Carneiro, 8-Sep-2015.)
|- D = ( abs o. - )   =>    |- ( R e. RR* -> ( `' abs " ( 0 [,) R ) ) = ( 0 ( ball ` D ) R ) )
Theorem	cnblcld 14925*	Two ways to write the closed ball centered at zero. (Contributed by Mario Carneiro, 8-Sep-2015.)
|- D = ( abs o. - )   =>    |- ( R e. RR* -> ( `' abs " ( 0 [,] R ) ) = { x e. CC | ( 0 D x ) <_ R } )
Theorem	cnfldms 14926	The complex number field is a metric space. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- ℂfld e. MetSp
Theorem	cnfldxms 14927	The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- ℂfld e. *MetSp
Theorem	cnfldtps 14928	The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- ℂfld e. TopSp
Theorem	cnfldtopn 14929	The topology of the complex numbers. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- J = ( TopOpen ` ℂfld )   =>    |- J = ( MetOpen ` ( abs o. - ) )
Theorem	cnfldtopon 14930	The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.)
|- J = ( TopOpen ` ℂfld )   =>    |- J e. (TopOn ` CC )
Theorem	cnfldtop 14931	The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.)
|- J = ( TopOpen ` ℂfld )   =>    |- J e. Top
Theorem	unicntopcntop 14932	The underlying set of the standard topology on the complex numbers is the set of complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.) (Revised by Jim Kingdon, 12-Dec-2023.)
|- CC = U. ( MetOpen ` ( abs o. - ) )
Theorem	unicntop 14933	The underlying set of the standard topology on the complex numbers is the set of complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.)
|- CC = U. ( TopOpen ` ℂfld )
Theorem	cnopncntop 14934	The set of complex numbers is open with respect to the standard topology on complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.) (Revised by Jim Kingdon, 12-Dec-2023.)
|- CC e. ( MetOpen ` ( abs o. - ) )
Theorem	cnopn 14935	The set of complex numbers is open with respect to the standard topology on complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.)
|- CC e. ( TopOpen ` ℂfld )
Theorem	reopnap 14936*	The real numbers apart from a given real number form an open set. (Contributed by Jim Kingdon, 13-Dec-2023.)
|- ( A e. RR -> { w e. RR | w # A } e. ( topGen ` ran (,) ) )
Theorem	remetdval 14937	Value of the distance function of the metric space of real numbers. (Contributed by NM, 16-May-2007.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- ( ( A e. RR /\ B e. RR ) -> ( A D B ) = ( abs ` ( A - B ) ) )
Theorem	remet 14938	The absolute value metric determines a metric space on the reals. (Contributed by NM, 10-Feb-2007.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- D e. ( Met ` RR )
Theorem	rexmet 14939	The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- D e. ( *Met ` RR )
Theorem	bl2ioo 14940	A ball in terms of an open interval of reals. (Contributed by NM, 18-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- ( ( A e. RR /\ B e. RR ) -> ( A ( ball ` D ) B ) = ( ( A - B ) (,) ( A + B ) ) )
Theorem	ioo2bl 14941	An open interval of reals in terms of a ball. (Contributed by NM, 18-May-2007.) (Revised by Mario Carneiro, 28-Aug-2015.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- ( ( A e. RR /\ B e. RR ) -> ( A (,) B ) = ( ( ( A + B ) / 2 ) ( ball ` D ) ( ( B - A ) / 2 ) ) )
Theorem	ioo2blex 14942	An open interval of reals in terms of a ball. (Contributed by Mario Carneiro, 14-Nov-2013.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- ( ( A e. RR /\ B e. RR ) -> ( A (,) B ) e. ran ( ball ` D ) )
Theorem	blssioo 14943	The balls of the standard real metric space are included in the open real intervals. (Contributed by NM, 8-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   =>    |- ran ( ball ` D ) C_ ran (,)
Theorem	tgioo 14944	The topology generated by open intervals of reals is the same as the open sets of the standard metric space on the reals. (Contributed by NM, 7-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.)
|- D = ( ( abs o. - ) |` ( RR X. RR ) )   &    |- J = ( MetOpen ` D )   =>    |- ( topGen ` ran (,) ) = J
Theorem	tgqioo 14945	The topology generated by open intervals of reals with rational endpoints is the same as the open sets of the standard metric space on the reals. In particular, this proves that the standard topology on the reals is second-countable. (Contributed by Mario Carneiro, 17-Jun-2014.)
|- Q = ( topGen ` ( (,) " ( QQ X. QQ ) ) )   =>    |- ( topGen ` ran (,) ) = Q
Theorem	resubmet 14946	The subspace topology induced by a subset of the reals. (Contributed by Jeff Madsen, 2-Sep-2009.) (Revised by Mario Carneiro, 13-Aug-2014.)
|- R = ( topGen ` ran (,) )   &    |- J = ( MetOpen ` ( ( abs o. - ) |` ( A X. A ) ) )   =>    |- ( A C_ RR -> J = ( R ↾t A ) )
Theorem	tgioo2cntop 14947	The standard topology on the reals is a subspace of the complex metric topology. (Contributed by Mario Carneiro, 13-Aug-2014.) (Revised by Jim Kingdon, 6-Aug-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- ( topGen ` ran (,) ) = ( J ↾t RR )
Theorem	rerestcntop 14948	The subspace topology induced by a subset of the reals. (Contributed by Mario Carneiro, 13-Aug-2014.) (Revised by Jim Kingdon, 6-Aug-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   &    |- R = ( topGen ` ran (,) )   =>    |- ( A C_ RR -> ( J ↾t A ) = ( R ↾t A ) )
Theorem	tgioo2 14949	The standard topology on the reals is a subspace of the complex metric topology. (Contributed by Mario Carneiro, 13-Aug-2014.)
|- J = ( TopOpen ` ℂfld )   =>    |- ( topGen ` ran (,) ) = ( J ↾t RR )
Theorem	rerest 14950	The subspace topology induced by a subset of the reals. (Contributed by Mario Carneiro, 13-Aug-2014.)
|- J = ( TopOpen ` ℂfld )   &    |- R = ( topGen ` ran (,) )   =>    |- ( A C_ RR -> ( J ↾t A ) = ( R ↾t A ) )
Theorem	addcncntoplem 14951*	Lemma for addcncntop 14952, subcncntop 14953, and mulcncntop 14954. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Jim Kingdon, 22-Oct-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   &    |- .+ : ( CC X. CC ) --> CC   &    |- ( ( a e. RR+ /\ b e. CC /\ c e. CC ) -> E. y e. RR+ E. z e. RR+ A. u e. CC A. v e. CC ( ( ( abs ` ( u - b ) ) < y /\ ( abs ` ( v - c ) ) < z ) -> ( abs ` ( ( u .+ v ) - ( b .+ c ) ) ) < a ) )   =>    |- .+ e. ( ( J tX J ) Cn J )
Theorem	addcncntop 14952	Complex number addition is a continuous function. Part of Proposition 14-4.16 of [Gleason] p. 243. (Contributed by NM, 30-Jul-2007.) (Proof shortened by Mario Carneiro, 5-May-2014.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- + e. ( ( J tX J ) Cn J )
Theorem	subcncntop 14953	Complex number subtraction is a continuous function. Part of Proposition 14-4.16 of [Gleason] p. 243. (Contributed by NM, 4-Aug-2007.) (Proof shortened by Mario Carneiro, 5-May-2014.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- - e. ( ( J tX J ) Cn J )
Theorem	mulcncntop 14954	Complex number multiplication is a continuous function. Part of Proposition 14-4.16 of [Gleason] p. 243. (Contributed by NM, 30-Jul-2007.) (Proof shortened by Mario Carneiro, 5-May-2014.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- x. e. ( ( J tX J ) Cn J )
Theorem	divcnap 14955*	Complex number division is a continuous function, when the second argument is apart from zero. (Contributed by Mario Carneiro, 12-Aug-2014.) (Revised by Jim Kingdon, 25-Oct-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   &    |- K = ( J ↾t { x e. CC | x # 0 } )   =>    |- ( y e. CC , z e. { x e. CC | x # 0 } |-> ( y / z ) ) e. ( ( J tX K ) Cn J )
Theorem	mpomulcn 14956*	Complex number multiplication is a continuous function. (Contributed by GG, 16-Mar-2025.)
|- J = ( TopOpen ` ℂfld )   =>    |- ( x e. CC , y e. CC |-> ( x x. y ) ) e. ( ( J tX J ) Cn J )
Theorem	fsumcncntop 14957*	A finite sum of functions to complex numbers from a common topological space is continuous. The class expression for B normally contains free variables k and x to index it. (Contributed by NM, 8-Aug-2007.) (Revised by Mario Carneiro, 23-Aug-2014.)
|- K = ( MetOpen ` ( abs o. - ) )   &    |- ( ph -> J e. (TopOn ` X ) )   &    |- ( ph -> A e. Fin )   &    |- ( ( ph /\ k e. A ) -> ( x e. X |-> B ) e. ( J Cn K ) )   =>    |- ( ph -> ( x e. X |-> sum_ k e. A B ) e. ( J Cn K ) )
Theorem	fsumcn 14958*	A finite sum of functions to complex numbers from a common topological space is continuous. The class expression for B normally contains free variables k and x to index it. (Contributed by NM, 8-Aug-2007.) (Revised by Mario Carneiro, 23-Aug-2014.)
|- K = ( TopOpen ` ℂfld )   &    |- ( ph -> J e. (TopOn ` X ) )   &    |- ( ph -> A e. Fin )   &    |- ( ( ph /\ k e. A ) -> ( x e. X |-> B ) e. ( J Cn K ) )   =>    |- ( ph -> ( x e. X |-> sum_ k e. A B ) e. ( J Cn K ) )
Theorem	expcn 14959*	The power function on complex numbers, for fixed exponent N, is continuous. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 23-Aug-2014.) Avoid ax-mulf 8030. (Revised by GG, 16-Mar-2025.)
|- J = ( TopOpen ` ℂfld )   =>    |- ( N e. NN0 -> ( x e. CC |-> ( x ^ N ) ) e. ( J Cn J ) )
9.2.7  Topological definitions using the reals
Syntax	ccncf 14960	Extend class notation to include the operation which returns a class of continuous complex functions.
class -cn->
Definition	df-cncf 14961*	Define the operation whose value is a class of continuous complex functions. (Contributed by Paul Chapman, 11-Oct-2007.)
|- -cn-> = ( a e. ~P CC , b e. ~P CC |-> { f e. ( b ^m a ) | A. x e. a A. e e. RR+ E. d e. RR+ A. y e. a ( ( abs ` ( x - y ) ) < d -> ( abs ` ( ( f ` x ) - ( f ` y ) ) ) < e ) } )
Theorem	cncfval 14962*	The value of the continuous complex function operation is the set of continuous functions from A to B. (Contributed by Paul Chapman, 11-Oct-2007.) (Revised by Mario Carneiro, 9-Nov-2013.)
|- ( ( A C_ CC /\ B C_ CC ) -> ( A -cn-> B ) = { f e. ( B ^m A ) | A. x e. A A. y e. RR+ E. z e. RR+ A. w e. A ( ( abs ` ( x - w ) ) < z -> ( abs ` ( ( f ` x ) - ( f ` w ) ) ) < y ) } )
Theorem	elcncf 14963*	Membership in the set of continuous complex functions from A to B. (Contributed by Paul Chapman, 11-Oct-2007.) (Revised by Mario Carneiro, 9-Nov-2013.)
|- ( ( A C_ CC /\ B C_ CC ) -> ( F e. ( A -cn-> B ) <-> ( F : A --> B /\ A. x e. A A. y e. RR+ E. z e. RR+ A. w e. A ( ( abs ` ( x - w ) ) < z -> ( abs ` ( ( F ` x ) - ( F ` w ) ) ) < y ) ) ) )
Theorem	elcncf2 14964*	Version of elcncf 14963 with arguments commuted. (Contributed by Mario Carneiro, 28-Apr-2014.)
|- ( ( A C_ CC /\ B C_ CC ) -> ( F e. ( A -cn-> B ) <-> ( F : A --> B /\ A. x e. A A. y e. RR+ E. z e. RR+ A. w e. A ( ( abs ` ( w - x ) ) < z -> ( abs ` ( ( F ` w ) - ( F ` x ) ) ) < y ) ) ) )
Theorem	cncfrss 14965	Reverse closure of the continuous function predicate. (Contributed by Mario Carneiro, 25-Aug-2014.)
|- ( F e. ( A -cn-> B ) -> A C_ CC )
Theorem	cncfrss2 14966	Reverse closure of the continuous function predicate. (Contributed by Mario Carneiro, 25-Aug-2014.)
|- ( F e. ( A -cn-> B ) -> B C_ CC )
Theorem	cncff 14967	A continuous complex function's domain and codomain. (Contributed by Paul Chapman, 17-Jan-2008.) (Revised by Mario Carneiro, 25-Aug-2014.)
|- ( F e. ( A -cn-> B ) -> F : A --> B )
Theorem	cncfi 14968*	Defining property of a continuous function. (Contributed by Mario Carneiro, 30-Apr-2014.) (Revised by Mario Carneiro, 25-Aug-2014.)
|- ( ( F e. ( A -cn-> B ) /\ C e. A /\ R e. RR+ ) -> E. z e. RR+ A. w e. A ( ( abs ` ( w - C ) ) < z -> ( abs ` ( ( F ` w ) - ( F ` C ) ) ) < R ) )
Theorem	elcncf1di 14969*	Membership in the set of continuous complex functions from A to B. (Contributed by Paul Chapman, 26-Nov-2007.)
|- ( ph -> F : A --> B )   &    |- ( ph -> ( ( x e. A /\ y e. RR+ ) -> Z e. RR+ ) )   &    |- ( ph -> ( ( ( x e. A /\ w e. A ) /\ y e. RR+ ) -> ( ( abs ` ( x - w ) ) < Z -> ( abs ` ( ( F ` x ) - ( F ` w ) ) ) < y ) ) )   =>    |- ( ph -> ( ( A C_ CC /\ B C_ CC ) -> F e. ( A -cn-> B ) ) )
Theorem	elcncf1ii 14970*	Membership in the set of continuous complex functions from A to B. (Contributed by Paul Chapman, 26-Nov-2007.)
|- F : A --> B   &    |- ( ( x e. A /\ y e. RR+ ) -> Z e. RR+ )   &    |- ( ( ( x e. A /\ w e. A ) /\ y e. RR+ ) -> ( ( abs ` ( x - w ) ) < Z -> ( abs ` ( ( F ` x ) - ( F ` w ) ) ) < y ) )   =>    |- ( ( A C_ CC /\ B C_ CC ) -> F e. ( A -cn-> B ) )
Theorem	rescncf 14971	A continuous complex function restricted to a subset is continuous. (Contributed by Paul Chapman, 18-Oct-2007.) (Revised by Mario Carneiro, 25-Aug-2014.)
|- ( C C_ A -> ( F e. ( A -cn-> B ) -> ( F |` C ) e. ( C -cn-> B ) ) )
Theorem	cncfcdm 14972	Change the codomain of a continuous complex function. (Contributed by Paul Chapman, 18-Oct-2007.) (Revised by Mario Carneiro, 1-May-2015.)
|- ( ( C C_ CC /\ F e. ( A -cn-> B ) ) -> ( F e. ( A -cn-> C ) <-> F : A --> C ) )
Theorem	cncfss 14973	The set of continuous functions is expanded when the codomain is expanded. (Contributed by Mario Carneiro, 30-Aug-2014.)
|- ( ( B C_ C /\ C C_ CC ) -> ( A -cn-> B ) C_ ( A -cn-> C ) )
Theorem	climcncf 14974	Image of a limit under a continuous map. (Contributed by Mario Carneiro, 7-Apr-2015.)
|- Z = ( ZZ>= ` M )   &    |- ( ph -> M e. ZZ )   &    |- ( ph -> F e. ( A -cn-> B ) )   &    |- ( ph -> G : Z --> A )   &    |- ( ph -> G ~~> D )   &    |- ( ph -> D e. A )   =>    |- ( ph -> ( F o. G ) ~~> ( F ` D ) )
Theorem	abscncf 14975	Absolute value is continuous. (Contributed by Paul Chapman, 21-Oct-2007.) (Revised by Mario Carneiro, 28-Apr-2014.)
|- abs e. ( CC -cn-> RR )
Theorem	recncf 14976	Real part is continuous. (Contributed by Paul Chapman, 21-Oct-2007.) (Revised by Mario Carneiro, 28-Apr-2014.)
|- Re e. ( CC -cn-> RR )
Theorem	imcncf 14977	Imaginary part is continuous. (Contributed by Paul Chapman, 21-Oct-2007.) (Revised by Mario Carneiro, 28-Apr-2014.)
|- Im e. ( CC -cn-> RR )
Theorem	cjcncf 14978	Complex conjugate is continuous. (Contributed by Paul Chapman, 21-Oct-2007.) (Revised by Mario Carneiro, 28-Apr-2014.)
|- * e. ( CC -cn-> CC )
Theorem	mulc1cncf 14979*	Multiplication by a constant is continuous. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Mario Carneiro, 30-Apr-2014.)
|- F = ( x e. CC |-> ( A x. x ) )   =>    |- ( A e. CC -> F e. ( CC -cn-> CC ) )
Theorem	divccncfap 14980*	Division by a constant is continuous. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Jim Kingdon, 9-Jan-2023.)
|- F = ( x e. CC |-> ( x / A ) )   =>    |- ( ( A e. CC /\ A # 0 ) -> F e. ( CC -cn-> CC ) )
Theorem	cncfco 14981	The composition of two continuous maps on complex numbers is also continuous. (Contributed by Jeff Madsen, 2-Sep-2009.) (Revised by Mario Carneiro, 25-Aug-2014.)
|- ( ph -> F e. ( A -cn-> B ) )   &    |- ( ph -> G e. ( B -cn-> C ) )   =>    |- ( ph -> ( G o. F ) e. ( A -cn-> C ) )
Theorem	cncfmet 14982	Relate complex function continuity to metric space continuity. (Contributed by Paul Chapman, 26-Nov-2007.) (Revised by Mario Carneiro, 7-Sep-2015.)
|- C = ( ( abs o. - ) |` ( A X. A ) )   &    |- D = ( ( abs o. - ) |` ( B X. B ) )   &    |- J = ( MetOpen ` C )   &    |- K = ( MetOpen ` D )   =>    |- ( ( A C_ CC /\ B C_ CC ) -> ( A -cn-> B ) = ( J Cn K ) )
Theorem	cncfcncntop 14983	Relate complex function continuity to topological continuity. (Contributed by Mario Carneiro, 17-Feb-2015.)
|- J = ( MetOpen ` ( abs o. - ) )   &    |- K = ( J ↾t A )   &    |- L = ( J ↾t B )   =>    |- ( ( A C_ CC /\ B C_ CC ) -> ( A -cn-> B ) = ( K Cn L ) )
Theorem	cncfcn1cntop 14984	Relate complex function continuity to topological continuity. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Mario Carneiro, 7-Sep-2015.) (Revised by Jim Kingdon, 16-Jun-2023.)
|- J = ( MetOpen ` ( abs o. - ) )   =>    |- ( CC -cn-> CC ) = ( J Cn J )
Theorem	cncfcn1 14985	Relate complex function continuity to topological continuity. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Mario Carneiro, 7-Sep-2015.)
|- J = ( TopOpen ` ℂfld )   =>    |- ( CC -cn-> CC ) = ( J Cn J )
Theorem	cncfmptc 14986*	A constant function is a continuous function on CC. (Contributed by Jeff Madsen, 2-Sep-2009.) (Revised by Mario Carneiro, 7-Sep-2015.)
|- ( ( A e. T /\ S C_ CC /\ T C_ CC ) -> ( x e. S |-> A ) e. ( S -cn-> T ) )
Theorem	cncfmptid 14987*	The identity function is a continuous function on CC. (Contributed by Jeff Madsen, 11-Jun-2010.) (Revised by Mario Carneiro, 17-May-2016.)
|- ( ( S C_ T /\ T C_ CC ) -> ( x e. S |-> x ) e. ( S -cn-> T ) )
Theorem	cncfmpt1f 14988*	Composition of continuous functions. -cn-> analogue of cnmpt11f 14674. (Contributed by Mario Carneiro, 3-Sep-2014.)
|- ( ph -> F e. ( CC -cn-> CC ) )   &    |- ( ph -> ( x e. X |-> A ) e. ( X -cn-> CC ) )   =>    |- ( ph -> ( x e. X |-> ( F ` A ) ) e. ( X -cn-> CC ) )
Theorem	cncfmpt2fcntop 14989*	Composition of continuous functions. -cn-> analogue of cnmpt12f 14676. (Contributed by Mario Carneiro, 3-Sep-2014.)
|- J = ( MetOpen ` ( abs o. - ) )   &    |- ( ph -> F e. ( ( J tX J ) Cn J ) )   &    |- ( ph -> ( x e. X |-> A ) e. ( X -cn-> CC ) )   &    |- ( ph -> ( x e. X |-> B ) e. ( X -cn-> CC ) )   =>    |- ( ph -> ( x e. X |-> ( A F B ) ) e. ( X -cn-> CC ) )
Theorem	addccncf 14990*	Adding a constant is a continuous function. (Contributed by Jeff Madsen, 2-Sep-2009.)
|- F = ( x e. CC |-> ( x + A ) )   =>    |- ( A e. CC -> F e. ( CC -cn-> CC ) )
Theorem	idcncf 14991	The identity function is a continuous function on CC. (Contributed by Jeff Madsen, 11-Jun-2010.) (Moved into main set.mm as cncfmptid 14987 and may be deleted by mathbox owner, JM. --MC 12-Sep-2015.) (Revised by Mario Carneiro, 12-Sep-2015.)
|- F = ( x e. CC |-> x )   =>    |- F e. ( CC -cn-> CC )
Theorem	sub1cncf 14992*	Subtracting a constant is a continuous function. (Contributed by Jeff Madsen, 2-Sep-2009.) (Proof shortened by Mario Carneiro, 12-Sep-2015.)
|- F = ( x e. CC |-> ( x - A ) )   =>    |- ( A e. CC -> F e. ( CC -cn-> CC ) )
Theorem	sub2cncf 14993*	Subtraction from a constant is a continuous function. (Contributed by Jeff Madsen, 2-Sep-2009.) (Proof shortened by Mario Carneiro, 12-Sep-2015.)
|- F = ( x e. CC |-> ( A - x ) )   =>    |- ( A e. CC -> F e. ( CC -cn-> CC ) )
Theorem	cdivcncfap 14994*	Division with a constant numerator is continuous. (Contributed by Mario Carneiro, 28-Dec-2016.) (Revised by Jim Kingdon, 26-May-2023.)
|- F = ( x e. { y e. CC | y # 0 } |-> ( A / x ) )   =>    |- ( A e. CC -> F e. ( { y e. CC | y # 0 } -cn-> CC ) )
Theorem	negcncf 14995*	The negative function is continuous. (Contributed by Mario Carneiro, 30-Dec-2016.)
|- F = ( x e. A |-> -u x )   =>    |- ( A C_ CC -> F e. ( A -cn-> CC ) )
Theorem	negfcncf 14996*	The negative of a continuous complex function is continuous. (Contributed by Paul Chapman, 21-Jan-2008.) (Revised by Mario Carneiro, 25-Aug-2014.)
|- G = ( x e. A |-> -u ( F ` x ) )   =>    |- ( F e. ( A -cn-> CC ) -> G e. ( A -cn-> CC ) )
Theorem	mulcncflem 14997*	Lemma for mulcncf 14998. (Contributed by Jim Kingdon, 29-May-2023.)
|- ( ph -> ( x e. X |-> A ) e. ( X -cn-> CC ) )   &    |- ( ph -> ( x e. X |-> B ) e. ( X -cn-> CC ) )   &    |- ( ph -> V e. X )   &    |- ( ph -> E e. RR+ )   &    |- ( ph -> F e. RR+ )   &    |- ( ph -> G e. RR+ )   &    |- ( ph -> S e. RR+ )   &    |- ( ph -> T e. RR+ )   &    |- ( ph -> A. u e. X ( ( abs ` ( u - V ) ) < S -> ( abs ` ( ( ( x e. X |-> A ) ` u ) - ( ( x e. X |-> A ) ` V ) ) ) < F ) )   &    |- ( ph -> A. u e. X ( ( abs ` ( u - V ) ) < T -> ( abs ` ( ( ( x e. X |-> B ) ` u ) - ( ( x e. X |-> B ) ` V ) ) ) < G ) )   &    |- ( ph -> A. u e. X ( ( ( abs ` ( [_ u / x ]_ A - [_ V / x ]_ A ) ) < F /\ ( abs ` ( [_ u / x ]_ B - [_ V / x ]_ B ) ) < G ) -> ( abs ` ( ( [_ u / x ]_ A x. [_ u / x ]_ B ) - ( [_ V / x ]_ A x. [_ V / x ]_ B ) ) ) < E ) )   =>    |- ( ph -> E. d e. RR+ A. u e. X ( ( abs ` ( u - V ) ) < d -> ( abs ` ( ( ( x e. X |-> ( A x. B ) ) ` u ) - ( ( x e. X |-> ( A x. B ) ) ` V ) ) ) < E ) )
Theorem	mulcncf 14998*	The multiplication of two continuous complex functions is continuous. (Contributed by Glauco Siliprandi, 29-Jun-2017.)
|- ( ph -> ( x e. X |-> A ) e. ( X -cn-> CC ) )   &    |- ( ph -> ( x e. X |-> B ) e. ( X -cn-> CC ) )   =>    |- ( ph -> ( x e. X |-> ( A x. B ) ) e. ( X -cn-> CC ) )
Theorem	expcncf 14999*	The power function on complex numbers, for fixed exponent N, is continuous. (Contributed by Glauco Siliprandi, 29-Jun-2017.)
|- ( N e. NN0 -> ( x e. CC |-> ( x ^ N ) ) e. ( CC -cn-> CC ) )
Theorem	cnrehmeocntop 15000*	The canonical bijection from ( RR X. RR ) to CC described in cnref1o 9754 is in fact a homeomorphism of the usual topologies on these sets. (It is also an isometry, if ( RR X. RR ) is metrized with the l<SUP>2</SUP> norm.) (Contributed by Mario Carneiro, 25-Aug-2014.)
|- F = ( x e. RR , y e. RR |-> ( x + ( _i x. y ) ) )   &    |- J = ( topGen ` ran (,) )   &    |- K = ( MetOpen ` ( abs o. - ) )   =>    |- F e. ( ( J tX J ) Homeo K )