New posts in combinatorics

What is the fundamental difference between choosing a ball and rolling a die type of problems in probability?

probability combinatorics probability-theory probability-distributions philosophy

Minimal number of moves needed to solve a "Lights Out" variant

Evaluating the sum over all strings made of two anticommuting terms

combinatorics permutations binomial-coefficients noncommutative-algebra

Number of ways Nim-sum is X

combinatorics combinatorial-game-theory

Determinant Formula for derangement of $n$ numbers?

linear-algebra combinatorics derangements

Vandermonde's Identity: How to find a closed formula for the given summation [duplicate]

combinatorics sequences-and-series

Counting 5-letter words that include at least one vowel

What is the probability that the digit sum of a randomly chosen integer between 0000 and 9999 is divisible by 5?

probability combinatorics discrete-mathematics

Prove that an equation with two integer variables has no solution [closed]

combinatorics factorial

What would you call a finite collection of unordered objects that are not necessarily distinct?

combinatorics elementary-set-theory notation permutations definition

Subset of knight's move in chess.

combinatorics chessboard

Showing classic combinatorial $4^n$ identity using Vandermonde - What goes wrong? [duplicate]

combinatorics summation binomial-coefficients

Number of ways to visit each of $8$ zoos at least once and at most $3$ times

Limit of $S(n) = \sum_{k=1}^{\infty} \left(1 - \prod_{j=1}^{n-1}\left(1-\frac{j}{2^k}\right)\right)$ - Part II

number-theory real-analysis combinatorics sequences-and-series asymptotics

Number of coefficients of multivariable polynomial

combinatorics polynomials

Playing with numbers form $1$ to $n^2$ in an $n\times n$ grid

combinatorics contest-math

Show that a connected graph on $n$ vertices is a tree if and only if it has $n-1$ edges.

combinatorics graph-theory proof-verification

Random walks on symmetric groups

probability combinatorics symmetric-groups random-walk

Showing Directly that Dyck Paths Satisfy the Catalan Recurrence

combinatorics recurrence-relations catalan-numbers

Random solving of a Rubik cube .

probability combinatorics expectation random-walk rubiks-cube