Theorem List for Intuitionistic Logic Explorer - 15501-15600 *Has distinct variable
group(s)
| Type | Label | Description |
| Statement |
| |
| Theorem | xblpnfps 15501 |
The infinity ball in an extended metric is the set of all points that
are a finite distance from the center. (Contributed by Mario Carneiro,
23-Aug-2015.) (Revised by Thierry Arnoux, 11-Mar-2018.)
|
  PsMet 
             
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| |
| Theorem | xblpnf 15502 |
The infinity ball in an extended metric is the set of all points that
are a finite distance from the center. (Contributed by Mario Carneiro,
23-Aug-2015.)
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| |
| Theorem | blpnf 15503 |
The infinity ball in a standard metric is just the whole space.
(Contributed by Mario Carneiro, 23-Aug-2015.)
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| Theorem | bldisj 15504 |
Two balls are disjoint if the center-to-center distance is more than the
sum of the radii. (Contributed by Mario Carneiro, 30-Dec-2013.)
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| Theorem | blgt0 15505 |
A nonempty ball implies that the radius is positive. (Contributed by
NM, 11-Mar-2007.) (Revised by Mario Carneiro, 23-Aug-2015.)
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| Theorem | bl2in 15506 |
Two balls are disjoint if they don't overlap. (Contributed by NM,
11-Mar-2007.) (Revised by Mario Carneiro, 23-Aug-2015.)
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| Theorem | xblss2ps 15507 |
One ball is contained in another if the center-to-center distance is
less than the difference of the radii. In this version of blss2 15510 for
extended metrics, we have to assume the balls are a finite distance
apart, or else will not even be in the infinity ball around
.
(Contributed by Mario Carneiro, 23-Aug-2015.) (Revised by
Thierry Arnoux, 11-Mar-2018.)
|
 PsMet                     
                          |
| |
| Theorem | xblss2 15508 |
One ball is contained in another if the center-to-center distance is
less than the difference of the radii. In this version of blss2 15510 for
extended metrics, we have to assume the balls are a finite distance
apart, or else will not even be in the infinity ball around
.
(Contributed by Mario Carneiro, 23-Aug-2015.)
|
                         
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| |
| Theorem | blss2ps 15509 |
One ball is contained in another if the center-to-center distance is
less than the difference of the radii. (Contributed by Mario Carneiro,
15-Jan-2014.) (Revised by Mario Carneiro, 23-Aug-2015.) (Revised by
Thierry Arnoux, 11-Mar-2018.)
|
   PsMet                              |
| |
| Theorem | blss2 15510 |
One ball is contained in another if the center-to-center distance is
less than the difference of the radii. (Contributed by Mario Carneiro,
15-Jan-2014.) (Revised by Mario Carneiro, 23-Aug-2015.)
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| Theorem | blhalf 15511 |
A ball of radius is contained in a ball of radius centered
at any point inside the smaller ball. (Contributed by Jeff Madsen,
2-Sep-2009.) (Proof shortened by Mario Carneiro, 14-Jan-2014.)
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| Theorem | blfps 15512 |
Mapping of a ball. (Contributed by NM, 7-May-2007.) (Revised by Mario
Carneiro, 23-Aug-2015.) (Revised by Thierry Arnoux, 11-Mar-2018.)
|
 PsMet               |
| |
| Theorem | blf 15513 |
Mapping of a ball. (Contributed by NM, 7-May-2007.) (Revised by Mario
Carneiro, 23-Aug-2015.)
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| |
| Theorem | blrnps 15514* |
Membership in the range of the ball function. Note that
    is the
collection of all balls for metric .
(Contributed by NM, 31-Aug-2006.) (Revised by Mario Carneiro,
12-Nov-2013.) (Revised by Thierry Arnoux, 11-Mar-2018.)
|
 PsMet  
     
           |
| |
| Theorem | blrn 15515* |
Membership in the range of the ball function. Note that
    is the
collection of all balls for metric .
(Contributed by NM, 31-Aug-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
|
            
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| |
| Theorem | xblcntrps 15516 |
A ball contains its center. (Contributed by NM, 2-Sep-2006.) (Revised
by Mario Carneiro, 12-Nov-2013.) (Revised by Thierry Arnoux,
11-Mar-2018.)
|
  PsMet 

 
          |
| |
| Theorem | xblcntr 15517 |
A ball contains its center. (Contributed by NM, 2-Sep-2006.) (Revised
by Mario Carneiro, 12-Nov-2013.)
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| Theorem | blcntrps 15518 |
A ball contains its center. (Contributed by NM, 2-Sep-2006.) (Revised
by Mario Carneiro, 12-Nov-2013.) (Revised by Thierry Arnoux,
11-Mar-2018.)
|
  PsMet 

          |
| |
| Theorem | blcntr 15519 |
A ball contains its center. (Contributed by NM, 2-Sep-2006.) (Revised
by Mario Carneiro, 12-Nov-2013.)
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| Theorem | xblm 15520* |
A ball is inhabited iff the radius is positive. (Contributed by Mario
Carneiro, 23-Aug-2015.)
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| Theorem | bln0 15521 |
A ball is not empty. It is also inhabited, as seen at blcntr 15519.
(Contributed by NM, 6-Oct-2007.) (Revised by Mario Carneiro,
12-Nov-2013.)
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| |
| Theorem | blelrnps 15522 |
A ball belongs to the set of balls of a metric space. (Contributed by
NM, 2-Sep-2006.) (Revised by Mario Carneiro, 12-Nov-2013.) (Revised by
Thierry Arnoux, 11-Mar-2018.)
|
  PsMet 
               |
| |
| Theorem | blelrn 15523 |
A ball belongs to the set of balls of a metric space. (Contributed by
NM, 2-Sep-2006.) (Revised by Mario Carneiro, 12-Nov-2013.)
|
               
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| |
| Theorem | blssm 15524 |
A ball is a subset of the base set of a metric space. (Contributed by
NM, 31-Aug-2006.) (Revised by Mario Carneiro, 12-Nov-2013.)
|
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| |
| Theorem | unirnblps 15525 |
The union of the set of balls of a metric space is its base set.
(Contributed by NM, 12-Sep-2006.) (Revised by Mario Carneiro,
12-Nov-2013.) (Revised by Thierry Arnoux, 11-Mar-2018.)
|
 PsMet         |
| |
| Theorem | unirnbl 15526 |
The union of the set of balls of a metric space is its base set.
(Contributed by NM, 12-Sep-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
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| |
| Theorem | blininf 15527 |
The intersection of two balls with the same center is the smaller of
them. (Contributed by NM, 1-Sep-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
|
         
                          inf  
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| |
| Theorem | ssblps 15528 |
The size of a ball increases monotonically with its radius.
(Contributed by NM, 20-Sep-2007.) (Revised by Mario Carneiro,
24-Aug-2015.) (Revised by Thierry Arnoux, 11-Mar-2018.)
|
   PsMet    
                   |
| |
| Theorem | ssbl 15529 |
The size of a ball increases monotonically with its radius.
(Contributed by NM, 20-Sep-2007.) (Revised by Mario Carneiro,
24-Aug-2015.)
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| Theorem | blssps 15530* |
Any point in a ball
can be centered in
another ball that is
a subset of .
(Contributed by NM, 31-Aug-2006.) (Revised by
Mario Carneiro, 24-Aug-2015.) (Revised by Thierry Arnoux,
11-Mar-2018.)
|
  PsMet 
             
  |
| |
| Theorem | blss 15531* |
Any point in a ball
can be centered in
another ball that is
a subset of .
(Contributed by NM, 31-Aug-2006.) (Revised by
Mario Carneiro, 24-Aug-2015.)
|
                       |
| |
| Theorem | blssexps 15532* |
Two ways to express the existence of a ball subset. (Contributed by NM,
5-May-2007.) (Revised by Mario Carneiro, 12-Nov-2013.) (Revised by
Thierry Arnoux, 11-Mar-2018.)
|
  PsMet 
                      |
| |
| Theorem | blssex 15533* |
Two ways to express the existence of a ball subset. (Contributed by NM,
5-May-2007.) (Revised by Mario Carneiro, 12-Nov-2013.)
|
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| |
| Theorem | ssblex 15534* |
A nested ball exists whose radius is less than any desired amount.
(Contributed by NM, 20-Sep-2007.) (Revised by Mario Carneiro,
12-Nov-2013.)
|
         
  
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| |
| Theorem | blin2 15535* |
Given any two balls and a point in their intersection, there is a ball
contained in the intersection with the given center point. (Contributed
by Mario Carneiro, 12-Nov-2013.)
|
          

          
       
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| |
| Theorem | blbas 15536 |
The balls of a metric space form a basis for a topology. (Contributed
by NM, 12-Sep-2006.) (Revised by Mario Carneiro, 15-Jan-2014.)
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| |
| Theorem | blres 15537 |
A ball in a restricted metric space. (Contributed by Mario Carneiro,
5-Jan-2014.)
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| |
| Theorem | xmeterval 15538 |
Value of the "finitely separated" relation. (Contributed by Mario
Carneiro, 24-Aug-2015.)
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| |
| Theorem | xmeter 15539 |
The "finitely separated" relation is an equivalence relation.
(Contributed by Mario Carneiro, 24-Aug-2015.)
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| Theorem | xmetec 15540 |
The equivalence classes under the finite separation equivalence relation
are infinity balls. (Contributed by Mario Carneiro, 24-Aug-2015.)
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| |
| Theorem | blssec 15541 |
A ball centered at is
contained in the set of points finitely
separated from . This is just an application of ssbl 15529
to the
infinity ball. (Contributed by Mario Carneiro, 24-Aug-2015.)
|
           
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| Theorem | blpnfctr 15542 |
The infinity ball in an extended metric acts like an ultrametric ball in
that every point in the ball is also its center. (Contributed by Mario
Carneiro, 21-Aug-2015.)
|
                               |
| |
| Theorem | xmetresbl 15543 |
An extended metric restricted to any ball (in particular the infinity
ball) is a proper metric. Together with xmetec 15540, this shows that any
extended metric space can be "factored" into the disjoint
union of
proper metric spaces, with points in the same region measured by that
region's metric, and points in different regions being distance
from each other. (Contributed by Mario Carneiro, 23-Aug-2015.)
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| 9.2.4 Open sets of a metric space
|
| |
| Theorem | mopnrel 15544 |
The class of open sets of a metric space is a relation. (Contributed by
Jim Kingdon, 5-May-2023.)
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| |
| Theorem | mopnval 15545 |
An open set is a subset of a metric space which includes a ball around
each of its points. Definition 1.3-2 of [Kreyszig] p. 18. The object
    is the family of all open sets in the metric space
determined by the metric . By mopntop 15547, the open sets of a
metric space form a topology , whose base set is  by
mopnuni 15548. (Contributed by NM, 1-Sep-2006.) (Revised
by Mario
Carneiro, 12-Nov-2013.)
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| |
| Theorem | mopntopon 15546 |
The set of open sets of a metric space is a topology on .
Remark in [Kreyszig] p. 19. This
theorem connects the two concepts and
makes available the theorems for topologies for use with metric spaces.
(Contributed by Mario Carneiro, 24-Aug-2015.)
|
          TopOn    |
| |
| Theorem | mopntop 15547 |
The set of open sets of a metric space is a topology. (Contributed by
NM, 28-Aug-2006.) (Revised by Mario Carneiro, 12-Nov-2013.)
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| Theorem | mopnuni 15548 |
The union of all open sets in a metric space is its underlying set.
(Contributed by NM, 4-Sep-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
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| Theorem | elmopn 15549* |
The defining property of an open set of a metric space. (Contributed by
NM, 1-Sep-2006.) (Revised by Mario Carneiro, 12-Nov-2013.)
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| Theorem | mopnfss 15550 |
The family of open sets of a metric space is a collection of subsets of
the base set. (Contributed by NM, 3-Sep-2006.) (Revised by Mario
Carneiro, 12-Nov-2013.)
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| Theorem | mopnm 15551 |
The base set of a metric space is open. Part of Theorem T1 of
[Kreyszig] p. 19. (Contributed by NM,
4-Sep-2006.) (Revised by Mario
Carneiro, 12-Nov-2013.)
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| Theorem | elmopn2 15552* |
A defining property of an open set of a metric space. (Contributed by
NM, 5-May-2007.) (Revised by Mario Carneiro, 12-Nov-2013.)
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| Theorem | mopnss 15553 |
An open set of a metric space is a subspace of its base set.
(Contributed by NM, 3-Sep-2006.)
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| Theorem | isxms 15554 |
Express the predicate "   is an extended metric space"
with underlying set and distance function . (Contributed by
Mario Carneiro, 2-Sep-2015.)
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| Theorem | isxms2 15555 |
Express the predicate "   is an extended metric space"
with underlying set and distance function . (Contributed by
Mario Carneiro, 2-Sep-2015.)
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| Theorem | isms 15556 |
Express the predicate "   is a metric space" with
underlying set
and distance function . (Contributed by NM,
27-Aug-2006.) (Revised by Mario Carneiro, 24-Aug-2015.)
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                          |
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| Theorem | isms2 15557 |
Express the predicate "   is a metric space" with
underlying set
and distance function . (Contributed by NM,
27-Aug-2006.) (Revised by Mario Carneiro, 24-Aug-2015.)
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| Theorem | xmstopn 15558 |
The topology component of an extended metric space coincides with the
topology generated by the metric component. (Contributed by Mario
Carneiro, 26-Aug-2015.)
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| Theorem | mstopn 15559 |
The topology component of a metric space coincides with the topology
generated by the metric component. (Contributed by Mario Carneiro,
26-Aug-2015.)
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| Theorem | xmstps 15560 |
An extended metric space is a topological space. (Contributed by Mario
Carneiro, 26-Aug-2015.)
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| Theorem | msxms 15561 |
A metric space is an extended metric space. (Contributed by Mario
Carneiro, 26-Aug-2015.)
|

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| Theorem | mstps 15562 |
A metric space is a topological space. (Contributed by Mario Carneiro,
26-Aug-2015.)
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| Theorem | xmsxmet 15563 |
The distance function, suitably truncated, is an extended metric on
. (Contributed
by Mario Carneiro, 2-Sep-2015.)
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| Theorem | msmet 15564 |
The distance function, suitably truncated, is a metric on .
(Contributed by Mario Carneiro, 12-Nov-2013.)
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| Theorem | msf 15565 |
The distance function of a metric space is a function into the real
numbers. (Contributed by NM, 30-Aug-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
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| Theorem | xmsxmet2 15566 |
The distance function, suitably truncated, is an extended metric on
. (Contributed
by Mario Carneiro, 2-Oct-2015.)
|
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| Theorem | msmet2 15567 |
The distance function, suitably truncated, is a metric on .
(Contributed by Mario Carneiro, 2-Oct-2015.)
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| Theorem | mscl 15568 |
Closure of the distance function of a metric space. (Contributed by NM,
30-Aug-2006.) (Revised by Mario Carneiro, 2-Oct-2015.)
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| Theorem | xmscl 15569 |
Closure of the distance function of an extended metric space.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
           
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| Theorem | xmsge0 15570 |
The distance function in an extended metric space is nonnegative.
(Contributed by Mario Carneiro, 4-Oct-2015.)
|
           
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| Theorem | xmseq0 15571 |
The distance between two points in an extended metric space is zero iff
the two points are identical. (Contributed by Mario Carneiro,
2-Oct-2015.)
|
           
    
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| Theorem | xmssym 15572 |
The distance function in an extended metric space is symmetric.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
           
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| Theorem | xmstri2 15573 |
Triangle inequality for the distance function of an extended metric.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
           
 
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| Theorem | mstri2 15574 |
Triangle inequality for the distance function of a metric space.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
         
  
        
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| Theorem | xmstri 15575 |
Triangle inequality for the distance function of a metric space.
Definition 14-1.1(d) of [Gleason] p.
223. (Contributed by Mario
Carneiro, 2-Oct-2015.)
|
           
 
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| Theorem | mstri 15576 |
Triangle inequality for the distance function of a metric space.
Definition 14-1.1(d) of [Gleason] p.
223. (Contributed by Mario
Carneiro, 2-Oct-2015.)
|
         
  
        
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| Theorem | xmstri3 15577 |
Triangle inequality for the distance function of an extended metric.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
           
 
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| Theorem | mstri3 15578 |
Triangle inequality for the distance function of a metric space.
(Contributed by Mario Carneiro, 2-Oct-2015.)
|
         
  
        
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| Theorem | msrtri 15579 |
Reverse triangle inequality for the distance function of a metric space.
(Contributed by Mario Carneiro, 4-Oct-2015.)
|
         
  
       
     
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| |
| Theorem | xmspropd 15580 |
Property deduction for an extended metric space. (Contributed by Mario
Carneiro, 4-Oct-2015.)
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| |
| Theorem | mspropd 15581 |
Property deduction for a metric space. (Contributed by Mario Carneiro,
4-Oct-2015.)
|
                    
             
      
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| Theorem | setsmsbasg 15582 |
The base set of a constructed metric space. (Contributed by Mario
Carneiro, 28-Aug-2015.)
|
                

sSet  TopSet  
       
              |
| |
| Theorem | setsmsdsg 15583 |
The distance function of a constructed metric space. (Contributed by
Mario Carneiro, 28-Aug-2015.)
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sSet  TopSet  
       
                  |
| |
| Theorem | setsmstsetg 15584 |
The topology of a constructed metric space. (Contributed by Mario
Carneiro, 28-Aug-2015.) (Revised by Jim Kingdon, 7-May-2023.)
|
                

sSet  TopSet  
       
            TopSet    |
| |
| Theorem | mopni 15585* |
An open set of a metric space includes a ball around each of its points.
(Contributed by NM, 3-Sep-2006.) (Revised by Mario Carneiro,
12-Nov-2013.)
|
                  
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| |
| Theorem | mopni2 15586* |
An open set of a metric space includes a ball around each of its points.
(Contributed by NM, 2-May-2007.) (Revised by Mario Carneiro,
12-Nov-2013.)
|
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| Theorem | mopni3 15587* |
An open set of a metric space includes an arbitrarily small ball around
each of its points. (Contributed by NM, 20-Sep-2007.) (Revised by
Mario Carneiro, 12-Nov-2013.)
|
            

         
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| Theorem | blssopn 15588 |
The balls of a metric space are open sets. (Contributed by NM,
12-Sep-2006.) (Revised by Mario Carneiro, 23-Dec-2013.)
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| Theorem | unimopn 15589 |
The union of a collection of open sets of a metric space is open.
Theorem T2 of [Kreyszig] p. 19.
(Contributed by NM, 4-Sep-2006.)
(Revised by Mario Carneiro, 23-Dec-2013.)
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| Theorem | mopnin 15590 |
The intersection of two open sets of a metric space is open.
(Contributed by NM, 4-Sep-2006.) (Revised by Mario Carneiro,
23-Dec-2013.)
|
             
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| Theorem | mopn0 15591 |
The empty set is an open set of a metric space. Part of Theorem T1 of
[Kreyszig] p. 19. (Contributed by NM,
4-Sep-2006.)
|
         
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| Theorem | rnblopn 15592 |
A ball of a metric space is an open set. (Contributed by NM,
12-Sep-2006.)
|
               
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| Theorem | blopn 15593 |
A ball of a metric space is an open set. (Contributed by NM,
9-Mar-2007.) (Revised by Mario Carneiro, 12-Nov-2013.)
|
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| Theorem | neibl 15594* |
The neighborhoods around a point of a metric space are those
subsets containing a ball around . Definition of neighborhood in
[Kreyszig] p. 19. (Contributed by NM,
8-Nov-2007.) (Revised by Mario
Carneiro, 23-Dec-2013.)
|
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| Theorem | blnei 15595 |
A ball around a point is a neighborhood of the point. (Contributed by
NM, 8-Nov-2007.) (Revised by Mario Carneiro, 24-Aug-2015.)
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| Theorem | blsscls2 15596* |
A smaller closed ball is contained in a larger open ball. (Contributed
by Mario Carneiro, 10-Jan-2014.)
|
                   
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| Theorem | metss 15597* |
Two ways of saying that metric generates a finer topology than
metric .
(Contributed by Mario Carneiro, 12-Nov-2013.) (Revised
by Mario Carneiro, 24-Aug-2015.)
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| Theorem | metequiv 15598* |
Two ways of saying that two metrics generate the same topology. Two
metrics satisfying the right-hand side are said to be (topologically)
equivalent. (Contributed by Jeff Hankins, 21-Jun-2009.) (Revised by
Mario Carneiro, 12-Nov-2013.)
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| Theorem | metequiv2 15599* |
If there is a sequence of radii approaching zero for which the balls of
both metrics coincide, then the generated topologies are equivalent.
(Contributed by Mario Carneiro, 26-Aug-2015.)
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| Theorem | metss2lem 15600* |
Lemma for metss2 15601. (Contributed by Mario Carneiro,
14-Sep-2015.)
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