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Combinatorics
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Number of ways to distribute 5 distinguishable balls between 3 kids such that each of them gets at least one ball
August 1st, 2022
combinatorics
Number of ways to color the edges of a tetrahedron with two colors?
August 1st, 2022
contest-math
permutations
combinatorics
How many combinations does Android pattern have?
August 1st, 2022
combinations
combinatorics
permutations
The Matching Problem/Derangements - n letters to n people
August 1st, 2022
combinatorics
probability
inclusion-exclusion
How to calculate this triple summation?
August 1st, 2022
summation
binomial-coefficients
algebra-precalculus
combinatorics
Arithmetic error in Feller's Introduction to Probability?
August 13th, 2022
probability
combinatorics
pigeonhole principle clarification
August 1st, 2022
pigeonhole-principle
combinatorics
probability
permutations of a multiset having symbols with fixed multiplicity
August 1st, 2022
combinatorics
permutations
multisets
Number of 6-digit passwords, starting with even or ending with odd digit
August 1st, 2022
combinatorics
discrete-mathematics
Using Exponential Generating Functions on Counting Problems
August 1st, 2022
combinatorics
$6$ women and $4$ men wait in line. If their order in line is random, find the probability that all of the women are adjacent to one another.
August 1st, 2022
permutations
combinatorics
Combinatorics - Catalan numbers recursive function proof by induction help
August 1st, 2022
induction
catalan-numbers
combinatorics
recurrence-relations
Combinatorial Identity $(n-r) \binom{n+r-1}{r} \binom{n}{r} = n \binom{n+r-1}{2r} \binom{2r}{r}$
August 1st, 2022
binomial-coefficients
combinatorics
combinatorial-proofs
Proof of stars and bars formula
August 1st, 2022
combinatorics
permutations
A standard and rigorous proof using the pigeonhole principle
August 1st, 2022
pigeonhole-principle
combinatorics
Parity of Perfect Matchings
August 1st, 2022
combinatorics
How can I assign weights to coins so that they can be counted in a single weighing?
August 14th, 2022
number-theory
combinatorics
Problem with Gambler's ruin
August 4th, 2022
random-walk
probability
combinatorics
probability-theory
markov-chains
Problems on combinatorics
August 15th, 2022
combinatorics
Is it possible to cover a $8 \times8$ board with $2 \times 1$ pieces?
August 1st, 2022
coloring
tiling
combinatorics
Determine the number of irreducible monic polynomials of degree 3 in $\mathbb F_p[x]$
August 1st, 2022
polynomials
combinatorics
finite-fields
abstract-algebra
Finding an "optimal" set of coin denominations
August 1st, 2022
combinatorics
Maximum area of triangle inside a convex polygon
August 1st, 2022
extremal-combinatorics
convex-geometry
combinatorics
polyhedra
combinatorial-geometry
number of combination in which no two red balls are adjacent.
May 8th, 2020
permutations
combinatorics
Combination Problem: Arranging letters of word DAUGHTER
August 12th, 2022
combinatorics
Puzzle: A coin rolls without slipping around another coin
August 1st, 2022
puzzle
algebra-precalculus
geometry
combinatorics
recreational-mathematics
Proof of $\sum_{0 \le k \le a} {a \choose k} {b \choose k} = {a+b \choose a}$
August 1st, 2022
binomial-coefficients
summation
combinatorics
Factorial decomposition of integers?
August 1st, 2022
number-systems
combinatorics
number-theory
What is the expected number of flips of an unfair coin until you have 2 more heads than tails?
August 1st, 2022
combinatorics
probability
A fair die is rolled n times. What is the probability that at least 1 of the 6 values never appears?
August 1st, 2022
probability
combinatorics
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