Voldemort
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 Apr11 awarded Popular Question Mar30 comment The number of $n$-tuples with a sum less than $m$ is $C_m^n$? You are absolutely right. How did I miss that? By the way @Solomon's answer is equivalent. The key point is summing. Mar30 accepted The number of $n$-tuples with a sum less than $m$ is $C_m^n$? Mar30 asked The number of $n$-tuples with a sum less than $m$ is $C_m^n$? Mar23 awarded Popular Question Mar11 awarded Yearling Dec10 accepted You only need countable many sets each time in a generated $\sigma$-algebra, right? Nov5 accepted How do I prove that $\cos{\frac{2\pi}{7}}\notin\mathbb{Q}$? Jul11 awarded Popular Question Jul2 awarded Curious Jul2 awarded Inquisitive Jun30 awarded Popular Question Jun2 awarded Popular Question Mar11 awarded Yearling Feb19 awarded Popular Question Dec16 accepted Why is this unbounded linear functional also has a closed kernel? Dec15 awarded Popular Question Dec11 accepted If a linear functional is not bounded, then it has a non-closed kernel. Dec11 comment If a linear functional is not bounded, then it has a non-closed kernel. Oh, I get it. It's because according to one of the definitions of unbounded linear operator, there exists $y_n$, with $\|y_n\|=1$ but $|f(y_n)|\to\infty$, now let $x_n=y_n/|f(y_n)|$ and we get what we want. Dec11 comment If a linear functional is not bounded, then it has a non-closed kernel. Why is $V/\ker f$ a finite dimensional space?