Counting Bubbles in Linear Chord Diagrams
Donovan Young
St Albans
Hertfordshire AL3 4HB
United Kingdom
Abstract:
In a linear chord diagram, a short chord is one that joins adjacent
vertices. We define a bubble to be a region in a linear chord diagram
devoid of short chords. We derive a formal generating function counting
bubbles by their size and find an exact result for the mean bubble
size. We find that once one discards diagrams that have no short chords
at all, the distribution of bubble sizes is given by a smooth function
in the limit of long diagrams. Using a summation over short chords,
we find the exact form of this asymptotic distribution.
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(Concerned with sequences
A079267
A278990
A367000.)
Received November 6 2023; revised versions received December 18 2023; February 12 2024.
Published in Journal of Integer Sequences,
March 18 2024.
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