On Geometric Drawings of Graphs

dc.contributor.authorArroyo Guevara, Alan Marcelo
dc.date.accessioned2018-04-18T16:26:51Z
dc.date.available2018-04-18T16:26:51Z
dc.date.issued2018-04-18
dc.date.submitted2018-04-17
dc.description.abstractThis thesis is about geometric drawings of graphs and their topological generalizations. First, we study pseudolinear drawings of graphs in the plane. A pseudolinear drawing is one in which every edge can be extended into an infinite simple arc in the plane, homeomorphic to $\mathbb{R}$, and such that every two extending arcs cross exactly once. This is a natural generalization of the well-studied class of rectilinear drawings, where edges are straight-line segments. Although, the problem of deciding whether a drawing is homeomorphic to a rectilinear drawing is NP-hard, in this work we characterize the minimal forbidden subdrawings for pseudolinear drawings and we also provide a polynomial-time algorithm for recognizing this family of drawings. Second, we consider the problem of transforming a topological drawing into a similar rectilinear drawing preserving the set of crossing pairs of edges. We show that, under some circumstances, pseudolinearity is a necessary and sufficient condition for the existence of such transformation. For this, we prove a generalization of Tutte's Spring Theorem for drawings with crossings placed in a particular way. Lastly, we study drawings of $K_n$ in the sphere whose edges can be extended to an arrangement of pseudocircles. An arrangement of pseudocircles is a set of simple closed curves in the sphere such that every two intersect at most twice. We show that (i) there is drawing of $K_{10}$ that cannot be extended into an arrangement of pseudocircles; and (ii) there is a drawing of $K_9$ that can be extended to an arrangement of pseudocircles, but no extension satisfies that every two pseudocircles intersects exactly twice. We also introduce the notion pseudospherical drawings of $K_n$, a generalization of spherical drawings in which each edge is a minor arc of a great circle. We show that these drawings are characterized by a simple local property. We also show that every pseudospherical drawing has an extension into an arrangement of pseudocircles where the ``at most twice'' condition is replaced by ``exactly twice''.en
dc.identifier.urihttp://hdl.handle.net/10012/13103
dc.language.isoenen
dc.pendingfalse
dc.publisherUniversity of Waterlooen
dc.subjectcombinatoricsen
dc.subjectcrossing numbersen
dc.subjectgraph theoryen
dc.subjectgraphen
dc.subjectdrawingen
dc.subjectcomplete graphen
dc.subjectrectilinearen
dc.subjectgraph embeddingen
dc.subjectgraph drawingen
dc.titleOn Geometric Drawings of Graphsen
dc.typeDoctoral Thesisen
uws-etd.degreeDoctor of Philosophyen
uws-etd.degree.departmentCombinatorics and Optimizationen
uws-etd.degree.disciplineCombinatorics and Optimizationen
uws-etd.degree.grantorUniversity of Waterlooen
uws.contributor.advisorRichter, Bruce
uws.contributor.affiliation1Faculty of Mathematicsen
uws.peerReviewStatusUnrevieweden
uws.published.cityWaterlooen
uws.published.countryCanadaen
uws.published.provinceOntarioen
uws.scholarLevelGraduateen
uws.typeOfResourceTexten

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