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I encountered an example that said:

A Tychonoff 2-starcompact space of countable spread which is not $1\frac{1}{2}$-starcompact.

My question is this: What's the meaning of "countable spread" ?

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    See [here](http://math.stackexchange.com/questions/105513/cardinality-of-a-discrete-subset).2012-06-30
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    There is a nice online reference: Apollo Hogan: [A Glossary of Definitions from General Topology](http://math.berkeley.edu/~apollo/topodefs.ps). Some cardinal functions are also mentioned at [Wikipedia](http://en.wikipedia.org/wiki/Cardinal_function#Cardinal_functions_in_topology). If you have a look at references given in the Wikipedia article, the books Juhász, István: [Cardinal functions in topology](http://oai.cwi.nl/oai/asset/13055/13055A.pdf) and Juhász, István: [Cardinal functions in topology - ten years later](http://oai.cwi.nl/oai/asset/12982/12982A.pdf) are devoted (cont...)2012-06-30
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    (...cont) exclusively to the cardinal functions and they are freely available online. (Many books from the Mathematical Centre Tracts series can be found [here](http://repository.cwi.nl/).) But you also find many facts about cardinal functions in standard references, such as Engelking's General Topology.2012-06-30
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    Thanks for the books link, Martin Sleziak.2012-06-30

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The question was answered in comments. Since we don't like leaving questions unanswered, I'll copy here the definitions from Wikipedia.

The cellularity of a space $X$ is $${\rm c}(X)=\sup\{|{\mathcal U}|:{\mathcal U}\text{ is a family of mutually disjoint non-empty open subsets of }X \}+\aleph_0.$$

The hereditary cellularity (sometimes spread) is the least upper bound of cellularities of its subsets: $$s(X)={\rm hc}(X)=\sup\{ {\rm c} (Y) : Y\subseteq X \}$$ or $$s(X)=\sup\{|Y|:Y\subseteq X \text{ with the subspace topology is discrete}\}+\aleph_0.$$