2026/07/19 by Romeo Meštrović · 1 voice
#math.HO #math.CO #math.NT
Let N be an arbitrary positive integer and let λ=(λ1, λ2, …, λl) be a partition of N of length l, i.e., ∑i=1lλi= N with parts λ1≥ λ2… λl≥ 1. Define T(λ) as the partition of N with parts l,λ1-1λ2-1,… λl-1,ignoring any zeros that might occur. Starting with a partition λ of N, we describe Bulgarian solitaire by repeatedly applying the shift operation T to obtain the sequence of partitions λ, T(λ), T2(λ),… . We say a partition μ of N is T-cyclic if T(μ) = μ for some i≥ 1. In 1982 Brandt [9] characterized all T-cyclic partitions for Bulgarian solitaire. Bulgarian solitaire is a dynamical system on integer partition of a positive integer N which converges to a unique fixed point if N=1+2+⋯ +k is a triangular number. In this paper we present a short survey of the game Bulgarian solitaire and several variations of this game.