julian fernandez
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 Dec26 asked Confusion between categoricity and indiscernability Dec26 accepted Indiscernibility of indiscernibles in second order logic Dec26 asked Indiscernibility of indiscernibles in second order logic Dec15 awarded Caucus Nov12 answered Addition in linear vector spaces Nov9 comment Can a hyperbolic quadrilateral have 3 obtuse angles and 3 equal sides? Not in hyperbolic space, but you can in elliptical space: just try to deform the second quadrilateral in elliptical geometry into the one you are imagining. Oct31 comment Why “a function continuous at only one point” is not an oxymoron? a "connected" line? (even if it were of infinitesimal length) Oct31 comment question about continuity or discontinuity of a function @DanZimm I posted my question here: math.stackexchange.com/questions/999320/… Oct31 asked Why “a function continuous at only one point” is not an oxymoron? Oct29 comment Find the value of k which makes f a density function. It is actually the inverse of that number. The integral must be equal to 1. Oct29 comment question about continuity or discontinuity of a function @DanZimm you are correct, thanks for the enlightenment! I still have trouble making sense of it. Continuity at only-one-point sounds like an oxymoron to my mind. Could it be that the classical definition of continuity fails to capture the concept of continuity for this pathological case? Or is it just me? I think I am going to post my own question about this. Oct29 revised question about continuity or discontinuity of a function added 46 characters in body Oct28 comment Minimization of the difference between two functions just write the equation between two arbitrary points on each line and minimize it (I assume you know calculus 101). Oct28 comment Show that $\int_{-1}^1f(t)dt = \sum_{i=1}^nw_if(a_i)$ Hailey, go back and read the calculus book again, please! Oct27 comment Numerical problem The easiest method is a calculator, and the answer is 1003003001 Oct27 comment Is this parametric equation correct? I just tried to combine two parameters so that I would get the line for some values and the point for others, and luckily it was easy. I am pretty sure there must be a recipe for it, but I do not remember it, I left college a long time ago. Oct27 comment Is this parametric equation correct? For what choices of s and t do you think your parametric equation gives (x,y,z)=(1,-2,4)? if there are no such s and t (there aren't), then the plane does not include that point. Oct27 revised Is this parametric equation correct? added 33 characters in body Oct27 answered Is this parametric equation correct? Oct12 comment What is the dimension for this subspace? 1) is a plane, so dimension=2, 2) is a line (intersection of two planes), so dimension=1