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Counting humps and peaks in generalized Motzkin paths
Authors:Toufik Mansour  Mark Shattuck
Affiliation:1. Department of Mathematics, University of Haifa, 31905 Haifa, Israel;2. Department of Mathematics, University of Tennessee, Knoxville, TN 37996, USA
Abstract:Let us call a lattice path in Z×Z from (0,0) to (n,0) using U=(1,k), D=(1,?1), and H=(a,0) steps and never going below the x-axis, a (k,a)-path (of order n). A super   (k,a)-path is a (k,a)-path which is permitted to go below the x-axis. We relate the total number of humps in all of the (k,a)-paths of order n to the number of super (k,a)-paths, where a hump is defined to be a sequence of steps of the form UHiD, i0. This generalizes recent results concerning the cases when k=1 and a=1 or a=. A similar relation may be given involving peaks (consecutive steps of the form UD).
Keywords:Dyck paths  Motzkin paths  Humps  Peaks
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