Results 1  10
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12
Planarizing Graphs  A Survey and Annotated Bibliography
, 1999
"... Given a finite, undirected, simple graph G, we are concerned with operations on G that transform it into a planar graph. We give a survey of results about such operations and related graph parameters. While there are many algorithmic results about planarization through edge deletion, the results abo ..."
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Cited by 32 (0 self)
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Given a finite, undirected, simple graph G, we are concerned with operations on G that transform it into a planar graph. We give a survey of results about such operations and related graph parameters. While there are many algorithmic results about planarization through edge deletion, the results about vertex splitting, thickness, and crossing number are mostly of a structural nature. We also include a brief section on vertex deletion. We do not consider parallel algorithms, nor do we deal with online algorithms.
The Thickness of Graphs: A Survey
 Graphs Combin
, 1998
"... We give a stateoftheart survey of the thickness of a graph from both a theoretical and a practical point of view. After summarizing the relevant results concerning this topological invariant of a graph, we deal with practical computation of the thickness. We present some modifications of a ba ..."
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Cited by 23 (0 self)
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We give a stateoftheart survey of the thickness of a graph from both a theoretical and a practical point of view. After summarizing the relevant results concerning this topological invariant of a graph, we deal with practical computation of the thickness. We present some modifications of a basic heuristic and investigate their usefulness for evaluating the thickness and determining a decomposition of a graph in planar subgraphs. Key words: Thickness, maximum planar subgraph, branch and cut 1 Introduction In VLSI circuit design, a chip is represented as a hypergraph consisting of nodes corresponding to macrocells and of hyperedges corresponding to the nets connecting the cells. A chipdesigner has to place the macrocells on a printed circuit board (which usually consists of superimposed layers), according to several designing rules. One of these requirements is to avoid crossings, since crossings lead to undesirable signals. It is therefore desirable to find ways to handle wi...
ThreeDimensional Orthogonal Graph Drawing with Optimal Volume
"... An orthogonal drawing of a graph is an embedding of the graph in the rectangular grid, with vertices represented by axisaligned boxes, and edges represented by paths in the grid which only possibly intersect at common endpoints. In this paper, we study threedimensional orthogonal drawings and prov ..."
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Cited by 23 (8 self)
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An orthogonal drawing of a graph is an embedding of the graph in the rectangular grid, with vertices represented by axisaligned boxes, and edges represented by paths in the grid which only possibly intersect at common endpoints. In this paper, we study threedimensional orthogonal drawings and provide lower bounds for three scenarios: (1) drawings where vertices have bounded aspect ratio, (2) drawings where the surface of vertices is proportional to their degree, and (3) drawings without any such restrictions. Then we show that these lower bounds are asymptotically optimal, by providing constructions that match the lower bounds in all scenarios within an order of magnitude.
Geometric Thickness in a Grid of Linear Area
 In [1
, 2001
"... this paper we consider a variation of geometric thickness which lies between thickness and geometric thickness in which each edge has at most one bend. We are also interested in drawings with small area, which is an important consideration in VLSI and visualisation. To measure the area of a drawing ..."
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Cited by 5 (2 self)
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this paper we consider a variation of geometric thickness which lies between thickness and geometric thickness in which each edge has at most one bend. We are also interested in drawings with small area, which is an important consideration in VLSI and visualisation. To measure the area of a drawing we assume a vertex resolution rule; that is, pairs of vertices are at least unitdistance apart. A drawing obtained from a book embedding by positioning the vertices around a circle, as discussed above, has O(n ) area. The construction in [DEH00] demonstrating that (Kn ) d 4 e has O(n 6 ) area [D. Eppstein, personal communication ]. We prove the following 2dimensional generalisation of the abovementioned result in [Mal94b] for producing book embeddings
Biplanar crossing numbers I: A Survey of Results and Problems
 IN: MORE SETS, GRAPHS AND NUMBERS
, 2006
"... We survey known results and propose open problems on the biplanar crossing number. We study biplanar crossing numbers of specific families of graphs, in particular, of complete bipartite graphs. We find a few particular exact values and give general lower and upper bounds for the biplanar crossing n ..."
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Cited by 5 (0 self)
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We survey known results and propose open problems on the biplanar crossing number. We study biplanar crossing numbers of specific families of graphs, in particular, of complete bipartite graphs. We find a few particular exact values and give general lower and upper bounds for the biplanar crossing number. We find the exact biplanar crossing number of K 5;q for every q.
Lower Bounds for the Number of Bends in ThreeDimensional Orthogonal Graph Drawings
, 2003
"... This paper presents the first nontrivial lower bounds for the total number of bends in 3D orthogonal graph drawings with vertices represented by points. In particular, we prove lower bounds for the number of bends in 3D orthogonal drawings of complete simple graphs and multigraphs, which are tigh ..."
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Cited by 4 (2 self)
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This paper presents the first nontrivial lower bounds for the total number of bends in 3D orthogonal graph drawings with vertices represented by points. In particular, we prove lower bounds for the number of bends in 3D orthogonal drawings of complete simple graphs and multigraphs, which are tight in most cases. These result are used as the basis for the construction of infinite classes of cconnected simple graphs, multigraphs, and pseudographs (2 &le; c &le; 6) of maximum degree &Delta; (3 &le; &Delta; &le; 6), with lower bounds on the total number of bends for all members of the class. We also present lower bounds for the number of bends in general position 3D orthogonal graph drawings. These results have significant ramifications for the `2bends problem', which is one of the most important open problems in the field.
A Note on Halton's Conjecture
"... The thickness of a graph G, is the minimum number of planar graphs, whose union is G. Halton conjectured ..."
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Cited by 2 (0 self)
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The thickness of a graph G, is the minimum number of planar graphs, whose union is G. Halton conjectured
Geometric Thickness in a Grid
 Discrete Mathematics
, 2001
"... The geometric thickness of a graph is the minimum number of layers such that the graph can be drawn in the plane with edges as straightline segments, and with each edge assigned to a layer so that no two edges on the same layer cross. We consider a variation on this theme in which each edge is allo ..."
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Cited by 2 (0 self)
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The geometric thickness of a graph is the minimum number of layers such that the graph can be drawn in the plane with edges as straightline segments, and with each edge assigned to a layer so that no two edges on the same layer cross. We consider a variation on this theme in which each edge is allowed one bend. We prove that the vertices of an nvertex medge graph can be positioned in a $$ grid and the edges assigned to $$ layers, so that each edge is drawn with at most one bend and no two edges on the same layer cross. The proof is a 2dimensional generalization of a theorem of S. M. Malitz [J. Algorithms 17(1):7184, 1994] on book embeddings. We obtain a Las Vegas algorithm to compute the drawing in O(m log n log log n) time (with high probability).
BoundedDegree Book Embedings and ThreeDimensional Orthogonal Graph Drawing
 Proc. 9th International Symp. on Graph Drawing (GD '01), volume 2265 of Lecture Notes in Comput. Sci
, 2002
"... A book embedding of a graph consists of a linear orderin of the vertices along a line in 3space (the spine), and an assignment of edges to halfplanes with the spine as boundary (the pages), so that edges assigned to the same page can be drawn on that page without crossings. Given a graph $G=(V,E)$ ..."
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A book embedding of a graph consists of a linear orderin of the vertices along a line in 3space (the spine), and an assignment of edges to halfplanes with the spine as boundary (the pages), so that edges assigned to the same page can be drawn on that page without crossings. Given a graph $G=(V,E)$, let $f:V\rightarrow\mathbb{N}$ be a function such that $1\leq f(v)\leq\deg(v)$. We present a Las Vegas algorithm which produces a book embedding of $G$ with \Oh{\sqrt{E\cdot\max_v\ceil{\deg(v)/f(v)}}} pages, such that at most $f(v)$ edges incident to a vertex $v$ are on a single page. This algorithm generalises existing results for book embeddings. We apply this algorithm to produce 3D orthogonal drawings with one bend per edge and \Oh{V^{3/2}E} volume, and \emph{singlerow} drawings with two bends per edge and the same volume. In the produced drawings each edge is entirely contained in some $Z$plane; such drawings are without socalled \emph{crosscuts}, and are particularly appropriate for applications in multilayer VLSI. Using a different approach, we achieve two bends per edge with \Oh{VE} volume but with crosscuts. These results establish improved bounds for the volume of 3D orthogonal graph drawings.