Computer science resolves around comutational processes. A process is a dynamic succession of events --a happening. When your computer is busy doing something, a process is going on inside it. What differentiates a computational process from some other kind of process(e.g., a chemical process)? Although computing originally referred to doing arithmetic, that isn't the essence of a computational process: For our purposes, a word, for example, enjoys the same status as a number, and looking up the word in a dictionary is as much a computational process as adding numbers. Nor does the process need to go inside a computer for it to be a computational process it could go in an old-fashioned library, where a patron turns the pages of a dictionary by hand.
What makes the process a computational process is that we study it in ways that ignore its physical nature. If we chose to study how the library patron turns the pages, perhaps by bending them to a certain point and then letting gravity flop them down, we would be looking at a mechanical process rather than a computational one. Here , on the other hand, is a computational description of the library patron's actions in looking up fiduciary:
- Because fiduciary starts with an f, he uses the dictionary's index tabs to locate the f section.
- Next, because the second letter is (i) is about a third of the way trough the alpahbet, he opens to a point roughly a third of the way into the f section.
- Finding herself slightly later in the alphabet (fiord), he then scans backward in a straightforward way, without any jumping about, until she finds fiduciary.
Notice that although there are some apparently physical terms in this description (index tab and section), the interesting thing about index tabs for the purposes of process description is not that they are tabs but that they allow one to zoom in on those entries of the dictionary that have a particular initial letter. If the dictionary were stroed in a computer, it could still have index tabs in the sense of some structure that allowed this operation, and essentially the same process could be used.