Interesting Esoterica

Topologically Distinct Sets of Non-intersecting Circles in the Plane

Article by Richard J. Mathar
  • Published in 2016
  • Added on
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Nested parentheses are forms in an algebra which define orders of evaluations. A class of well-formed sets of associated opening and closing parentheses is well studied in conjunction with Dyck paths and Catalan numbers. Nested parentheses also represent cuts through circles on a line. These become topologies of non-intersecting circles in the plane if the underlying algebra is commutative. This paper generalizes the concept and answers quantitatively - as recurrences and generating functions of matching rooted forests - the questions: how many different topologies of nested circles exist in the plane if (i) pairs of circles may intersect, or (ii) even triples of circles may intersect. That analysis is driven by examining the symmetry properties of the inner regions of the fundamental type(s) of the intersecting pairs and triples.

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key
TopologicallyDistinctSetsofNonintersectingCirclesinthePlane
type
article
date_added
2016-08-25
date_published
2016-03-14

BibTeX entry

@article{TopologicallyDistinctSetsofNonintersectingCirclesinthePlane,
	key = {TopologicallyDistinctSetsofNonintersectingCirclesinthePlane},
	type = {article},
	title = {Topologically Distinct Sets of Non-intersecting Circles in the Plane},
	author = {Richard J. Mathar},
	abstract = {Nested parentheses are forms in an algebra which define orders of
evaluations. A class of well-formed sets of associated opening and closing
parentheses is well studied in conjunction with Dyck paths and Catalan numbers.
Nested parentheses also represent cuts through circles on a line. These become
topologies of non-intersecting circles in the plane if the underlying algebra
is commutative.
  This paper generalizes the concept and answers quantitatively - as
recurrences and generating functions of matching rooted forests - the
questions: how many different topologies of nested circles exist in the plane
if (i) pairs of circles may intersect, or (ii) even triples of circles may
intersect. That analysis is driven by examining the symmetry properties of the
inner regions of the fundamental type(s) of the intersecting pairs and triples.},
	comment = {},
	date_added = {2016-08-25},
	date_published = {2016-03-14},
	urls = {http://arxiv.org/abs/1603.00077v1,http://arxiv.org/pdf/1603.00077v1},
	collections = {Easily explained,Geometry},
	url = {http://arxiv.org/abs/1603.00077v1 http://arxiv.org/pdf/1603.00077v1},
	urldate = {2016-08-25},
	archivePrefix = {arXiv},
	eprint = {1603.00077},
	primaryClass = {math.CO},
	year = 2016
}