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I'm not quite sure why this seems to be so controversial, except for the light abuse of notation in my english. Saying that f: X->Y means f maps an input from d
by kian 3y ago
I'm not quite sure why this seems to be so controversial, except for the light abuse of notation in my english. Saying that f: X->Y means f maps an input from domain X to output in range Y is to say that we are defining a function -- and labeling it f, since it could just as easily be labeled g and still be the same function. Defining is naming -- naming is labeling [with scope].
- OJFord 3y agoIt's not defining a function though, it's describing (by one aspect) a whole class of functions. Take: f: ints -> ints f can be 'add1', 'identity', 'double', etc. If you know that, and calling it 'defining a function' is just loose English (you didn't mean completely defining) then fine, but that's what's confusing people. It read to me like you thought it was equivalent to a function definition in code, X & Y described what would actually happen over different inputs, so I was just trying to explain, didn't mean to offend if you knew already.
- kian 3y agoOooh, I see what you're saying. For want of an "s". Yes, in this context, I am aware that it is a whole class of functions -- and that f is a label being affixed to that class of functions. Sorry for the confusion -- that makes much more sense now. No offense received -- was just genuinely confused as to why it netted two comments and a few downvotes for a seemingly uncontroversial statement. But then again, we're talking mathematical logic here, so loose english is of course reasonably discouraged. Thanks for the clarification, and I hope you have a great evening!