Published online by Cambridge University Press: 28 February 2011
We present a CAT (constant amortized time) algorithm for generating those partitions of n that are in the ice pile model $\mbox{IPM}_k$ (n),a generalization of the sand pile model $\mbox{SPM}$
(n).More precisely, for any fixed integer k, we show thatthe negative lexicographic ordering naturally identifies a tree structure on the lattice $\mbox{IPM}_k$
(n):this lets us design an algorithm which generates all the ice piles of $\mbox{IPM}_k$
(n)in amortized timeO(1)and in spaceO( $\sqrt n$
).