SF Site

SF Site is a webzine edited by Rodger Turner. Established in 1996 by John O'Neill, it is based in Canada, but includes contributors from around the world. It publishes reviews of science fiction books, films, and television, and features interviews with authors and fiction excerpts. Contributors include Steven H Silver, Richard Lupoff, Rick Norwood, Victoria Strauss, Mark London Williams, and Rick Klaw.

It is also the web hosting for notable science fiction and fantasy authors such as Guy Gavriel Kay and Charles de Lint and magazines such as Fantasy and Science Fiction. It hosts a science fiction discussion forum and RSS feed. In 2002, it won the Locus Award for best science fiction webzine.

In December 2013, SF Site suspended production of regular twice-monthly updates, due to declining advertising revenue.

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Site

Site may refer to:

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In mathematics:

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Sitež

Sitež is a settlement in the Municipality of Majšperk in northeastern Slovenia. It lies in the Haloze Hills on the regional road from Majšperk to Žetale. The area is part of the traditional region of Styria. It is now included with the rest of the municipality in the Drava statistical region.

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Grothendieck topology

In category theory, a branch of mathematics, a Grothendieck topology is a structure on a category C which makes the objects of C act like the open sets of a topological space. A category together with a choice of Grothendieck topology is called a site.

Grothendieck topologies axiomatize the notion of an open cover. Using the notion of covering provided by a Grothendieck topology, it becomes possible to define sheaves on a category and their cohomology. This was first done in algebraic geometry and algebraic number theory by Alexander Grothendieck to define the étale cohomology of a scheme. It has been used to define other cohomology theories since then, such as l-adic cohomology, flat cohomology, and crystalline cohomology. While Grothendieck topologies are most often used to define cohomology theories, they have found other applications as well, such as to John Tate's theory of rigid analytic geometry.

There is a natural way to associate a site to an ordinary topological space, and Grothendieck's theory is loosely regarded as a generalization of classical topology. Under meager point-set hypotheses, namely sobriety, this is completely accurate—it is possible to recover a sober space from its associated site. However simple examples such as the indiscrete topological space show that not all topological spaces can be expressed using Grothendieck topologies. Conversely, there are Grothendieck topologies which do not come from topological spaces.