Can portions of my PhD thesis be later submitted to conferences?
In computer science in general, you can submit thesis extracts to conference just as freely as you would submit them to a journal.  In both cases, the principle is the same: a thesis is not really a peer-reviewed publication, so your submission would still be the first peer-reviewed publication of the material.  You must, however, cite your thesis and clearly acknowledge the source of the material as being adapted from your thesis.