Alexis, all computer programs employ Boolean logic. All search engines, by definition, must use it. As soon as you enter your search terms, the search engine must use a statement like "Return the page's URL if the metadata on the HTML page contains these terms".




I'm not sure. It seems straight-forward enough when you say it, but I keep thinking about fuzzy logic programs. I'm no expert, though, and I've only written two of the little buggers. Just to see what it's all about, but I'm still confused about the fuss. One of my best friends' thesis advisor was Lofti Zadeh (the guy who formulated fuzzy logic). He used to talk about it all the time, but I had trouble following the point. Zadeh subbed in one of my other classes once, and it would've been nice to get word straight from the horse's mouth, but but it was a different subject and he didn't mention FL.

I would *like* to disgree with you (not to be disagreeable, but because it strikes me that you might be wrong), but the only examples I have of FL actually implement the code in binary logic - I mean, they have to, since the opcodes are based on binary logic. So I guess I answered my own point - at some level they all have to use binary logic - which makes you right after all.

I note (and maybe this is obvious to everyone) that there are several binary "logics." There is propositional calculus (probably what most people mean by it). There is also predicate calculus (or First Order Logic, FOL) which is a superset of propositional calculus and which is what programming languages like Prolog are based on (as well as many AI related programs). There are also extensions of FOL to temporal logics (these are used with path planning algorithms).

BTW, there was an article in last month's WIRED about search engines that was pretty interesting and not too technical.

Oh, and while it's true that digital computers have to use binary logic, it's not necessarily true that all computers will always use it. There are neural chips for pattern recognition without logic. If quantum computers take off, there may be yet another kind of logic that is used to program them (I don't know whether it will be mutually exclusive to FOL, but it the programs do look funny - maybe it's an extension of FOL?).


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