Academia.edu no longer supports Internet Explorer.
To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser.
1984, Proceedings of the sixteenth annual ACM symposium on Theory of computing - STOC '84
We provide an algorithm which solves the following problem: given a polygon with edges parallel to the x and y axes, which is convex in the y direction, find a minimum size collection of rectangles, which cover the polygon and are contained within it. The algorithm is quadratic in the number of vertices of the polygon. Our method also yields a new proof of a recent duality theorem equating minimum size rectangle covers to maximum size sets of independent points in the polygon.
Information and Control, 1984
Decomposing a polygon into simple shapes is a basic problem in computational geometry, with applications in pattern recognition and integrated circuit manufacture. Here we examine the special case of covering a rectilinear polygon (or polyomino) with the minimum number of rectangles, with overlapping allowed. The problem is NP-hard. However, we give here an O(v z) algorithm for constructing a minimum rectangle cover, when the polygon is vertically convex. (Here v is the number of vertices.) The problem is first reduced to a 1-dimensional interval "basis" problem. In showing our algorithm produces an optimal cover we give a new proof of a minimum basis-maximum independent set duality theorem first proved by E.
SIAM Journal on Algebraic …, 1981
A board 3 is a finite set of unit squares lying in the plane whose corners have integer coordinates. A rectangle of is a rectangular subset of and an antirectangle is a set of squares in no two of which are in a common rectangle. We prove a conjecture of Chvfital that if 3 is convex in the horizontal and vertical directions, then the minimum number of rectangles whose union is equals the maximum cardinality of an antirectangle. Our proof uses two analogous minimax theorems about covering the corners and covering the edges of the board.
Journal of Experimental Algorithmics, 2007
We consider the problem of covering an orthogonal polygon with a minimum number of axis-parallel rectangles from a computational point of view. We propose an integer program which is the first general approach to obtain provably optimal solutions to this well-studied N P-hard problem. It applies to common variants like covering only the corners or the boundary of the polygon, and also to the weighted case. In experiments it turns out that the linear programming relaxation is extremely tight, and rounding a fractional solution is an immediate high quality heuristic. We obtain excellent experimental results for polygons originating from VLSI design, fax data sheets, black and white images, and for random instances. Making use of the dual linear program, we propose a stronger lower bound on the optimum, namely the cardinality of a fractional stable set. We outline ideas how to make use of this bound in primal-dual based algorithms. We give partial results which make us believe that our proposals have a strong potential to settle the main open problem in the area: To find a constant factor approximation algorithm for the rectangle cover problem.
ArXiv, 2019
We study the problem of finding maximum-area rectangles contained in a polygon in the plane. There has been a fair amount of work for this problem when the rectangles have to be axis-aligned or when the polygon is convex. We consider this problem in a simple polygon with $n$ vertices, possibly with holes, and with no restriction on the orientation of the rectangles. We present an algorithm that computes a maximum-area rectangle in $O(n^3\log n)$ time using $O(kn^2)$ space, where $k$ is the number of reflex vertices of $P$. Our algorithm can report all maximum-area rectangles in the same time using $O(n^3)$ space. We also present a simple algorithm that finds a maximum-area rectangle contained in a convex polygon with $n$ vertices in $O(n^3)$ time using $O(n)$ space.
1995
We consider the problem of reporting the pairwise enclosures among a set of n axes-parallel rectangles in IR 2 , which is equivalent to reporting dominance pairs in a set of n points in IR 4 . For more than ten years, it has been an open problem whether these problems can be solved faster than in O(n log 2 n + k) time, where k denotes the number of reported pairs. First, we give a divide-and-conquer algorithm that matches the O(n) space and O(n log 2 n + k) time bounds of the algorithm of Lee and Preparata LP82], but is simpler. Then we give another algorithm that uses O(n) space and runs in O(n log n log log n+k log log n) time. For the special case where the rectangles have at most di erent aspect ratios, we give an algorithm that runs in O( n log n + k) time and uses O(n) space. Problem 1.1 Given a set R of n axes-parallel rectangles in the plane, report all pairs (R 0 ; R) of rectangles such that R encloses R 0 .
1998
Given a convex polygon P with m vertices and a set S of n points in the plane, we consider the problem of nding a placement o f P that contains the maximum number of points in S. We allow both translation and rotation. Our algorithm is self-contained and utilizes the geometric properties of the containing regions in the parameter space of transformations. The algorithm requires O(nk 2 m 2 log(mk)) time and O(n + m) space, where k is the maximum number of points contained. This provides a linear improvement o ver the best previously known algorithm when k is large ((n)) and a cubic improvement w h e n k is small. We also show that the algorithm can be extended to solve bichromatic and general weighted variants of the problem.
Discrete Mathematics, 1990
We prove that given n 2 3 convex, compact, and pairwise disjoint sets in the plane, they may be covered with n non-overlapping convex polygons with a total of not more than 6n -9 sides, and with not more than 3n -6 distinct slopes. Furthermore, we construct sets that require 6n -9 sides and 3n -6 slopes for n 2 3. The upper bound on the number of slopes implies a new bound on a recently studied transversal problem.
Abstract A set of circles, rectangles, and convex polygons are to be cut from rectangular design plates to be produced, or from a set of stocked rectangles of known geometric dimensions. The objective is to minimize the area of the design rectangles. The design plates are subject to lower and upper bounds of their widths and lengths. The objects are free of any orientation restrictions.
Information Processing Letters, 2002
We consider the following problem as defined by Grove et al. [Internat. J. Comput. Geom. Appl. 9 (1999) 207-217]: Given a set of n isothetic rectangles in 3D space determine the subset of rectangles, that are not completely hidden. We present an optimal algorithm for this problem that runs in O(n log n) time and O(n) space. Our result is an improvement over the one of Grove et al. by a logarithmic factor in storage and is achieved by using a different approach. An analogous approach gives non-trivial solutions for other kinds of objects too.
The Visual Computer, 1985
A generalized problem is defined in terms of functions on sets and illustrated in terms of the computational geometry of simple planar polygons. Although its apparent time complexity is O (n2), the problem is shown to be solvable for several cases of interest (maximum and minimum distance, intersection detection and rerporting) in O (n log n), O (n), or O (log n) time, depending on the nature of a specialized "selection" function. (Some of the cases can also be solved by the Voronoi diagram method; but time complexity increases with that approach.) A new use of monotonicity and a new concept of" locality" in set mappings contribute significantly to the derivation of the results.
International Journal of Computational Geometry & Applications, 2011
Given a set S of n points in the plane, the disjoint two-rectangle covering problem is to find a pair of disjoint rectangles such that their union contains S and the area of the larger rectangle is minimized. In this paper we consider two variants of this optimization problem: (1) the rectangles are allowed to be reoriented freely while restricting them to be parallel to each other, and (2) one rectangle is restricted to be axis-parallel but the other rectangle is allowed to be reoriented freely. For both of the problems, we present O(n2 log n)-time algorithms using O(n) space.
Discrete Applied Mathematics, 2007
Given a rectangle R with area and a set of n positive reals A = {a 1 , a 2 ,. .. , a n } with a i ∈A a i = , we consider the problem of dissecting R into n rectangles r i with area a i (i = 1, 2,. .. , n) so that the set R of resulting rectangles minimizes an objective function such as the sum of the perimeters of the rectangles in R, the maximum perimeter of the rectangles in R, and the maximum aspect ratio of the rectangles in R, where we call the problems with these objective functions PERI-SUM, PERI-MAX and ASPECT-RATIO, respectively. We propose an O(n log n) time algorithm that finds a dissection R of R that is a 1.25-approximate solution to PERI-SUM, a 2 √ 3-approximate solution to PERI-MAX, and has an aspect ratio at most max{ (R), 3, 1 + max i=1,...,n−1 a i+1 a i }, where (R) denotes the aspect ratio of R.
arXiv (Cornell University), 2019
Given a set of disjoint simple polygons σ 1 ,. .. , σ n , of total complexity N , consider a convexification process that repeatedly replaces a polygon by its convex hull, and any two (by now convex) polygons that intersect by their common convex hull. This process continues until no pair of polygons intersect. We show that this process has a unique output, which is a cover of the input polygons by a set of disjoint convex polygons, of total minimum area. Furthermore, we present a near linear time algorithm for computing this partition. The more general problem of covering a set of N segments (not necessarily disjoint) by min-area disjoint convex polygons can also be computed in near linear time. A similar result is already known, see the work by Barba et al. [BBBS13].
International Conference on Computing: Theory and Applications, 2007
We consider the problem of nding two parallel rectangles, in arbitrary orientation, covering a given set of n points in a plane, such that the area of the larger rectangle is minimized. We give a simple algorithm that solves the problem in O(n3) time using O(n2) space. Without altering the complexity, the algorithm can be modied to solve another optimization
We flnd minimal enclosures by rectangles for two and three regions of given areas. We show that each minimizer has connected regions and has shape depending on ratio of areas.
SIAM Journal on Computing, 1988
We solve the problem of decomposing a rectangle R into p rectangles of equal area so that the maximum rectangle perimeter is as small as possible. This work has applications in areas such as flexible object packing and data allocation. Our solution requires only a constant number of arithmetic operations and integer square roots to characterize the decomposition, and linear time to print the decomposition. The discrete analogue of the problem in which the rectangle R is replaced by a rectangular array of lattice points is also considered, and three heuristic methods of solution are given. All of the heuristic methods operate by finding a discrete approximation to our optimal decomposition of R, but with different tradeoffs between the accuracy of the approximation and running time.
Lecture Notes in Computer Science, 2009
In wireless communication networks, optimal use of the directional antenna is very important. The directional antenna coverage (DAC) problem is to cover all clients with the smallest number of directional antennas. In this paper, we consider the variable-size rectangle covering (VSRC) problem, which is a transformation of the DAC problem. There are n points above the base line y = 0 of the two-dimensional plane. The target is to cover all these points by minimum number of rectangles, such that the dimension of each rectangle is not fixed but the area is at most 1, and the bottom edge of each rectangle is on the base line y = 0. In some applications, the number of rectangles covering any position in the two-dimensional plane is bounded, so we also consider the variation when each position in the plane is covered by no more than two rectangles. We give two polynomial time algorithms for finding the optimal covering. Further, we propose two 2-approximation algorithms that use less running time (O(n log n) and O(n)).
Computational Geometry, 1996
A Tk guard G in a rectilinear polygon P is a tree of diameter k completely contained in P. The guard G is said to cover a point x if x is visible or rectangularly visible from some point c o n tained in G. W e i n vestigate the function rn h k, which i s t h e largest number of Tk guards necessary to cover any rectilinear polygon with h holes and n vertices. The aim of this paper is to prove n e w l o wer and upper bounds on parts of this function. In particular, we s h o w the following bounds: 1. rn 0 k n k+4 , with equality for even k 2. rn h 1 = 3n+4h+4 16 3. rn h 2 n 6. These bounds, along with other lower bounds that we establish, suggest that the presence of holes reduces the number of guards required, if k 1. In the course of proving the upper bounds, new results on partitioning are obtained.
… of the ninth annual symposium on …, 1993
e discuss problems of optimizing the area of a simple polygon for a given set of vertices P and show that thleSe problems are very closely related to problems of optimizing the number of points from a set Q in a simple polygon with vertex set P. We prove that it is NPcomplete to find a minimum weight polygon or a miiximum weight polygon for a given vertex set, resulting in a proof of NP-completeness for the corresponding area optimization problems. We show that we can find a polygon of more than half the area AR(conv(P)) of the convex hull conv(p) of P, and demonstrate that it is NPcomplete to decide whether there is a simple polygon of at least (~+ e)AR(COW(P)). Finally, we prove that for 1< k < d, 2< d, it is NP-hard to minimize the volume of the k-dimensional faces of a d-dimensional simple nondegenerate polyhedron with a given vertex set, answering a generalization of a question stated by O 'Rourke in 1980.
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.