Combinatorics 🧮

The poetry of Steiner systems

A Steiner triple system consists of a set S (such as the set of seven letters {A, E, H, R, T, W, Y}) together with a set of 3-element subsets of S…

Nov 14 •

How many cylinders can touch each other?

Oct 13 •

Matroid bingo is a simplified version of the game of bingo.

Sep 15 •

Transparent rectangle visibility graphs

A graph consists of a set of vertices, some of which are joined in pairs by edges.

Sep 1 •

Games in projective space

Projective geometry is a version of geometry in which there are points, lines, and planes, but in which there are no such things as distance or parallel…

Jun 16 •

Venn diagrams and Winkler’s conjecture

A Venn diagram is an extremely well known device for representing the logical relationships between three sets.

Apr 6 •

Counting dimer tilings

A dimer is a 2×1 domino-shaped rectangle.

Feb 21 •

The maximum number of SETs for 12 cards

SET is a card game that is played with a deck of 81 cards.

Feb 10 •

Identifying bottlenecks in networks

A large network, such as an infrastructure network or a social network, may contain highly connected regions that are linked to each other by…

Feb 3 •

Constructing space-filling curves

A curve that reaches every point in the unit square is known as a space-filling curve. One of the most famous space-filling curves is the Hilbert curve…

Dec 30, 2024 •

Chess and the number e

The number e=2.718281828459045… is one of the most famous irrational numbers.

Dec 16, 2024 •

The Parks puzzle

The Parks puzzle is a Sudoku-like game that is played on a square grid containing different coloured regions known as parks. The objective is to place…

Nov 11, 2024 •

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