Robert G. Donnelly

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The numbers game is a one-player game played on a finite simple graph with certain " amplitudes " assigned to its edges and with an initial assignment of real numbers to its nodes. The moves of the game successively transform the numbers at the nodes using the amplitudes in a certain way. This game and its interactions with Coxeter/Weyl group theory and Lie(More)
For a rank two root system and a pair of nonnegative integers, using only elementary com-binatorics we construct two posets. The constructions are uniform across the root systems We then form the dis-tributive lattices of order ideals of these posets. Corollary 5.4 gives elegant quotient-of-products expressions for the rank generating functions of these(More)
We associate one or two posets (which we call " semistandard posets ") to any given irreducible representation of a rank two semisimple Lie algebra over C. Elsewhere we have shown how the distributive lattices of order ideals taken from semis-tandard posets (we call these " semistandard lattices ") can be used to obtain certain information about these(More)
The numbers game is a one-player game played on a finite simple graph with certain " amplitudes " assigned to its edges and with an initial assignment of real numbers to its nodes. The moves of the game successively transform the numbers at the nodes using the amplitudes in a certain way. This game and its interactions with Coxeter/Weyl group theory and Lie(More)