A honeycomb of order n is a web of edges in three directions at 120°. Honeycombs parametrise Littlewood–Richardson coefficients — the multiplicities in tensor products of U(n) representations — and equivalently the eigenvalues of sums of Hermitian matrices (Horn's problem). The three boundary "spectra" A, B, C are those eigenvalue tuples. Click a hexagon to shrink it (right-click to enlarge); edges may shrink to zero but not go negative. The dual hive (a triangular array of integers) is shown at right.
A modern JavaScript + Canvas port of a 1998 Java applet by Terence Tao and
Allen Knutson (originally Honeycomb.java).
Click a hexagon to shrink it (right-click to enlarge). The Shrink / Enlarge / Max buttons act on your last-clicked hexagon — or on several at once if you set click to "select hexagons" and pick them (shown grey). Shrink All deflates the whole honeycomb by one layer.