Wrapping up my series about endgames from the Sicilian, we will be discussing the relevance of the major open lines in that structure: the c- and d-files.
In the basic Open Sicilian structure, White generally has primacy on the d-file and Black on the c-file. Indeed, how Black deals with the problem of the d-file affects the whole character of the game - if he plays ...e6 it is a Scheveningen, if ...e5 it is a Boleslavsky System, and if the e-pawn stays on e7 (thus keeping d6 solidly defended) it is a Dragon. Meanwhile, across the spectrum of Sicilians, there is one thing in common: the importance of the ...d5 break. In this way, Black can fight back and even assume the initiative on the d-file. In this instructive game by Tal, Black manages to make this break under good circumstances and eventually overruns White's position:
Another kind of metamorphosis can happen when Black captures a minor piece (usually a bishop) on d3. White often has a choice whether to recapture with the pawn on c2 or with some other piece:
More often than not, the capture with the pawn is preferable. Although it shuts down the d-file - and in some cases appears, at least superficially, to expose the white king - capturing with the pawn (as I did in the above position) does several things. By fully opening the c-file White relieves pressure against c2 and allows him to challenge, and often usurp, the c-file. Additionally, by capturing with the pawn, White strengthens e4, usually blunting a bishop on the long diagonal.
A positional theme which might not seem obvious at first, but should eventually be appreciated, is the idea to give up the two bishops and go into the ending after cxd3. As it turns out, this ending is often very favorable for White. Here is a good example, where Nigel Short overpowers his opponent in instructive fashion.
The Sicilian is a mysterious world, and despite the frequently very sharp nature of the game, understanding plays a dominant role in success as opposed to a simple rote memorization of variations. For this it is crucial to arm oneself with an understanding of the various structures which can arise.