The book "Computer Science - Theory and Applications" presents the refereed contributions of the Third International Symposium on Computer Science held in Russia in 2008 in Moscow. It includes 33 revised articles as well as 5 invited contributions and an opening speech, selected from a total of 103 submitted papers. The publication covers all essential areas of computer science and offers both theoretical and application-oriented perspectives. The theoretical part addresses topics such as algorithms, protocols, data structures, complexity, cryptography, formal languages, and their applications in computer science. The application part includes programming, computer architecture, hardware design, symbolic computation, numerical applications, as well as artificial intelligence and robotics. This comprehensive collection of works is a valuable resource for professionals and students who wish to engage with the latest developments in computer science.