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 Jan 15 answered Everything in math that we have found and proved to be TRUE so far will remain true forever? Jan 15 comment Integrability of $f\left(\frac1n\right)=\frac1n$ and else $f(x)=-1$ If your function differs from $f(x)=-1$ only on a subset of the rationals (measure 0) then that won't affect the value of a Lebesgue integral. Dec 24 awarded Tumbleweed Dec 17 asked Does this integral of Appell F_1 converge? Jan 8 awarded Commentator Jan 8 comment Is arrow notation for vectors “not mathematically mature”? Since nobody seems to have mentioned it, if you want to know how to notate something then read books until you find one you like, then copy that. Dec 23 comment Do we really need reals? I would say that in physics measurements produce distributions, which are then sampled over rationals. That is to say if you measure something with a ruler your result will be something that looks like a Gaussian around whatever you read off the scale, and then you'll say something like "the value is between 0.55m and 0.56m with 95% certainty". Dec 2 comment Is it possible to simulate a floor() function with elementary arithmetic? Replace invertible by continuous then. Oct 5 awarded Promoter Oct 2 asked ODEs of the form $a''= -f(b,t) b',\,\,\, b''=f(b,t) a'$ Sep 16 comment Ambiguity of notation: $\sin(x)^2$ Just worth pointing out that many people have thought the $sin^2$ notation (meaning the square of the sine) senseless for a long time, for example Charles Babbage[0]. I cannot understand how any right thinking person would use it, but many still do. [0] books.google.ie/… Aug 25 comment Why is there no natural metric on manifolds? This is a great physics answer. Aug 16 comment Is there an interval notation for complex numbers? @alexqwx it's not a matter of being sensible, they mean different things! The former (probably needing round brackets) makes $z$ a complex number, the latter makes it an interval. Jul 7 awarded Editor Jul 7 revised A simple limit problem the limit isn't the function! Jul 7 suggested approved edit on A simple limit problem Apr 21 answered Continuity and simplification of a function Apr 6 comment How to prove the quotient rule? Using exponents on functions like that really looks like functional composition (or inverse) rather than multiplicative. Feb 4 comment integral from zero to zero but if $\int_0^0 \delta=1$ then we also have $\int_0^0 \delta=\int_0^0 \delta+\int_0^0 \delta = 2$ May 18 awarded Critic