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| author | bnewbold <bnewbold@eta.mit.edu> | 2008-11-05 02:18:57 -0500 | 
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| committer | bnewbold <bnewbold@eta.mit.edu> | 2008-11-05 02:18:57 -0500 | 
| commit | a2d7b8c246db71e6c06e9f3db267b5a98691228d (patch) | |
| tree | 72631ba0571ae419280c4a388679cbabd55adfc6 /math | |
| parent | 930e322b9d0959b5a2067d9893b9d9ad92e64f56 (diff) | |
| download | knowledge-a2d7b8c246db71e6c06e9f3db267b5a98691228d.tar.gz knowledge-a2d7b8c246db71e6c06e9f3db267b5a98691228d.zip  | |
fixed latex math?
Diffstat (limited to 'math')
| -rw-r--r-- | math/topology | 62 | 
1 files changed, 31 insertions, 31 deletions
diff --git a/math/topology b/math/topology index 104cbe8..c7e482f 100644 --- a/math/topology +++ b/math/topology @@ -8,29 +8,29 @@ Topology  A *topological space* is a set for which a valid topology has been defined: the topology   determines which subsets of the topological space are open and closed. In this way the -concept of open and closed subsets on the real number line (such as `$(0,1)$`:latex: and -`$[1,2]$`:latex:) are generalized to arbitrary sets. +concept of open and closed subsets on the real number line (such as `$(0,1)$`:m: and +`$[1,2]$`:m:) are generalized to arbitrary sets. -Formally, a *topology* on a set `$A$`:latex: is a collection `$\mathcal{T}$`:latex: of  -subsets of `$A$`:latex: fufiling the criteria: +Formally, a *topology* on a set `$A$`:m: is a collection `$\mathcal{T}$`:m: of  +subsets of `$A$`:m: fufiling the criteria: - 1. The empty set and the entire set `$A$`:latex: are both in `$\mathcal{T}$`:latex:. + 1. The empty set and the entire set `$A$`:m: are both in `$\mathcal{T}$`:m:. - 2. The union of an arbitrary number of elements of `$\mathcal{T}$`:latex: is  -    also in `$\mathcal{T}$`:latex:. + 2. The union of an arbitrary number of elements of `$\mathcal{T}$`:m: is  +    also in `$\mathcal{T}$`:m:. - 3. The intersection of a finite number of elements of `$\mathcal{T}$`:latex: is -    also in `$\mathcal{T}$`:latex:. + 3. The intersection of a finite number of elements of `$\mathcal{T}$`:m: is +    also in `$\mathcal{T}$`:m:. -If a subset `$B$`:latex: of `$A$`:latex: is a member of `$\mathcal{T}$`:latex: then -`$B$`:latex: is an open set under the topology `$\mathcal{T}$`:latex:. +If a subset `$B$`:m: of `$A$`:m: is a member of `$\mathcal{T}$`:m: then +`$B$`:m: is an open set under the topology `$\mathcal{T}$`:m:.  *Coarseness* and *Fineness* are ways of comparing two topologies on the same space. -`$\mathcal{T'}$`:latex: is finer than `$\mathcal{T}$`:latex: if `$\mathcal{T}$`:latex: -is a subset of `$\mathcal{T'}$`:latex: (and `$\mathcal{T}$`:latex: is coarser);  -it is *strictly finer* if it is a proper subset (and `$\mathcal{T}$`:latex: is  -*strictly coarser*). Two sets are *comprable* if either `$\mathcal{T\in T'}$`:latex: -or `$\mathcal{T'\in T}$`:latex:. +`$\mathcal{T'}$`:m: is finer than `$\mathcal{T}$`:m: if `$\mathcal{T}$`:m: +is a subset of `$\mathcal{T'}$`:m: (and `$\mathcal{T}$`:m: is coarser);  +it is *strictly finer* if it is a proper subset (and `$\mathcal{T}$`:m: is  +*strictly coarser*). Two sets are *comprable* if either `$\mathcal{T\in T'}$`:m: +or `$\mathcal{T'\in T}$`:m:.  *Smaller* and *larger* are somtimes used instead of finer and coarser.  Topologies can be generated from a *basis*.  @@ -41,35 +41,35 @@ Frequently Used Topologies  *Standard Topology*      The standard topology on the real line is generated by the collection of all intervals  -    `$$(a,b)=\{x|a<x<b\}$$`:latex: +    `$$(a,b)=\{x|a<x<b\}$$`:m:      This is the usual definition for open sets on the real line.  *Discrete Topology* -    The topology on a set `$A$`:latex: consisting of all points of `$A$`:latex:; -    in other words the power set of `$A$`:latex:. +    The topology on a set `$A$`:m: consisting of all points of `$A$`:m:; +    in other words the power set of `$A$`:m:.  *Trivial/Indiscrete Topology* -    The topology on a set `$A$`:latex: consisting of only the empty set and `$A$`:latex: -    itself. Not super interesting but it's always there (when `$A$`:latex: isn't empty). +    The topology on a set `$A$`:m: consisting of only the empty set and `$A$`:m: +    itself. Not super interesting but it's always there (when `$A$`:m: isn't empty). -*Finite Complement Topology* (`$\mathcal{T_f}$`:latex:) -    The topology on a set `$A$`:latex: consisting of the empty set any subset  -    `$U$`:latex: such that `$A-U$`:latex: has a finite number of elements. +*Finite Complement Topology* (`$\mathcal{T_f}$`:m:) +    The topology on a set `$A$`:m: consisting of the empty set any subset  +    `$U$`:m: such that `$A-U$`:m: has a finite number of elements. -*Lower Limit Topology* (`$\mathbb{R}_\mathcal{l}$`:latex:) +*Lower Limit Topology* (`$\mathbb{R}_\mathcal{l}$`:m:)      The lower limit topology on the real line is generated by the collection of all half open      intervals -    `$$[a,b)=\{x|a\leq x<b\}$$`:latex: -    `$\mathbb{R}_\mathcal{l}$`:latex: is strictly finer than the standard topology and -    is not comprable to `$\mathbb{R}_K$`:latex:. +    `$$[a,b)=\{x|a\leq x<b\}$$`:m: +    `$\mathbb{R}_\mathcal{l}$`:m: is strictly finer than the standard topology and +    is not comprable to `$\mathbb{R}_K$`:m:. -*K-Topology* (`$\mathbb{R}_K$`:latex:) +*K-Topology* (`$\mathbb{R}_K$`:m:)      Let `$K$`:m: denote the set of all numbers `$1/n$`:n: where `$n$`:m: is      a positive integer.       The K-topology on the real line is generated by the collection of all standard open intervals       minus `$K$`:m:.  -    `$\mathbb{R}_K$`:latex: is strictly finer than the standard topology and is not -    comprable to `$\mathbb{R}_\mathcal{l}$`:latex:. +    `$\mathbb{R}_K$`:m: is strictly finer than the standard topology and is not +    comprable to `$\mathbb{R}_\mathcal{l}$`:m:.  *Order Topology*      TODO  | 
