Brian M. Scott
Reputation
331,808
396/400 score
 1d revised power set problem MathJax, formatting. 1d revised The definition of a metric and the triangle inequality Improved the English. 2d revised Expressing as a composite function to begin differentiating with the chain rule Corrected ‘derivating’ to ‘differentiating’. 2d revised Expressing as a composite function to begin differentiating with the chain rule Title, MathJax Nov 24 revised Evaluate $\sum_{k=0}^n (-1)^k{n \choose k}{m-k \choose r}$ using generating functions. Removed superfluous word. Nov 24 revised Finding a line tangent to two points of a graph WITHOUT calculus Edited picture and graph. Nov 23 revised Proving that $\chi(G) = \omega(G)$ if $\bar{G}$ is bipartite. Typo. Nov 23 revised Use inclusion-exclusion principle to count permutations where no number $i$ is followed by $i+1$ added 242 characters in body Nov 22 revised properties of relation product Changed $\Bbb R$ to $R$, since we’re not talking about the real line. Nov 22 revised Graph Theory (How many trees) Converted image to MathJax. Nov 22 revised Determine the language accepted by this DFA (in English) Added image. Nov 22 revised Using generating functions find the sum $1^3 + 2^3 + 3^3 +\dotsb+ n^3$ Added missing coefficient in penultimate displayed line. Nov 22 revised Existance of a nonempty subset $X$ of $\mathbb{Z}$: $\forall x \in X, k \in \mathbb{N}, \exists ! y \in X$ satisfying $\mid x-y \mid 2^k$ added 241 characters in body Nov 21 revised Closed form expression for $\sum_{k=0}^{n}(k^2 + 3k + 2)$ added 456 characters in body Nov 21 revised Recurrence relation for ordering n items from k different types Imported image. Nov 21 revised Construct a deterministic Turing machine that decides the language $L=\{w\in\{a, b\}\mid w\text{ contains an occurrence of }ab\}$ Imported image; MathJax. Nov 21 revised Upper bound for the size of a maximal collection of subsets which, pairwise, have at most one common element Typos. Nov 19 revised Use the Inclusion-Exclusion Principle to show that for any non-negative integers $m, r, n$ such that $m≤r≤n$… Added missing parentheses. Nov 18 revised $U\subset [0,\infty)$ is open and unbounded $\Rightarrow \exists x$ such that $U\cap \{nx;n\in \mathbb N\}$ is infinite. rolled back to a previous revision Nov 18 revised Which of the following are recursive formulas for the nth term of the following geometric sequence? edited tags