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An example of an abstract concept is the Church-Turing thesis. If you study the historical background of the thesis, including the problems leading up to the development of the Turing machine and the lambda calculus, if you learn how to take intuitive mental pictures of logical processes and formalize them equivalently in terms of Turing machines and lambda calculus expressions, if you understand exactly why the thesis is successful, and if you draw useful conclusions from the thesis, then you are studying computer science.</p>