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A bijection between bargraphs and Dyck paths. (English) Zbl 1401.05146
Summary: Bargraphs are a special class of column-convex polyominoes. They can be identified with lattice paths with unit steps north, east, and south that start at the origin, end on the $$x$$-axis, and stay strictly above the $$x$$-axis everywhere except at the endpoints. Bargraphs, which are used to represent histograms and to model polymers in statistical physics, have been enumerated in the literature by semiperimeter and by several other statistics, using different methods such as the wasp-waist decomposition of Feretić, and a bijection with certain Motzkin paths.
In this paper we describe an unusual bijection between bargraphs and Dyck paths, and study how some statistics are mapped by the bijection. As a consequence, we obtain a new interpretation of Catalan numbers, as counting bargraphs where the semiperimeter minus the number of peaks is fixed.

##### MSC:
 05C30 Enumeration in graph theory 05B50 Polyominoes
##### Keywords:
bargraph; bijection; Dyck path; Catalan number
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##### References:
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