Abstract
We show that a minimum coverage of a grid of n segments has n–p 3 weakly cooperative guards, where p 3 is the size of the maximum P 3-matching in the intersection graph of the grid. This makes the minimum weakly cooperative guards problem in grids NP-hard, as we prove that the maximum P 3-matching problem in subcubic bipartite planar graphs is NP-hard. At last, we propose a 7/6-approximation algorithm for the minimum weakly cooperative guards problem.
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Berman, F., Johnson, D., Leighton, T., Shor, P.W., Snyder, L.: Generalized planar matching. J. Algorithms 11, 153–184 (1990)
Czyżowicz, J., Kranakis, E., Urrutia, J.: A simple proof of the representation of bipartite planar graphs as the contact graphs of orthogonal straight line segments. Info. Proc. Lett. 66, 125–126 (1998)
De Bontridder, K.M.J., Haldórsson, B.V., Haldórsson, M.M., Hurkens, C.A.J., Lenstra, J.K., Ravi, R., Stougie, L.: Approximation algorithms for the test cover problem. Mathematical Programming 98, 477–491 (2003)
Deogun, J.S., Sarasamma, S.T.: On the minimum cooperative guards problem. J. Combin. Math. Combin. Comput. 22, 161–182 (1996)
Dyer, M.E., Frieze, A.M.: Planar 3DM is NP-complete. J. Algorithms 7, 174–184 (1986)
Finke, U., Hinchirs, K.: Overlaying simply connected planar subdivisions in linear time. In: Proc. 11th Annu. ACM Sympos. Comput. Geom., pp. 119–126 (1995)
Garey, M.R., Johnson, D.S.: Computers and Intractability: A Guide to the Theorey of NP-completeness. Freeman, New York (1979)
Hell, P., Kirkpatrick, D.G.: On the complexity of general graph factor problems. SIAM Journal of Comput. 12, 601–609 (1983)
Hernández-Peñalver, G.: Controlling guards. In: Proc. of Sixth Canadian Conference on Computational Geometry, pp. 387–392 (1994)
Liaw, B.C., Lee, R.C.T.: An optimal algorithm to solve the minimum weakly cooperative guards problem for 1-spiral polygons. Info. Proc. Lett. 57, 69–75 (1994)
Liaw, B.C., Huang, N.F., Lee, R.C.T.: The minimum cooperative guards problem on k-spiral polygons. In: Proc. of Fifth Canadian Conference on Computational Geometry, pp. 97–101 (1993)
Masuyama, S., Ibaraki, T.: Chain packing in graphs. Algorithmica 6, 826–839 (1991)
Nierhoff, T., Żyliński, P.: Cooperative guards in grids. In: Third Annual CGC Workshop (2003)
Ntafos, S.: On gallery watchman in grids. Info. Proc. Lett. 23, 99–102 (1986)
O’Rourke, J.: Art Gallery Theorems and Algorithms. Oxford University Press, Oxford (1987)
Urrutia, J.: Art Gallery and Illumination Problems, Handbook on Computational Geometry. Elsevier Science, Amsterdam (2000)
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Małafiejski, M., Żyliński, P. (2005). Weakly Cooperative Guards in Grids. In: Gervasi, O., et al. Computational Science and Its Applications – ICCSA 2005. ICCSA 2005. Lecture Notes in Computer Science, vol 3480. Springer, Berlin, Heidelberg. https://doi.org/10.1007/11424758_68
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DOI: https://doi.org/10.1007/11424758_68
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-25860-5
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