dehne@scs.carleton.CA (Frank Dehne) (07/23/90)
FINAL PROGRAM Second Canadian Conference in Computational Geometry August 6-10, 1990 University of Ottawa Ottawa, Canada Program Committee: Jurek Czyzowicz (Univ. du Queb c Hull) Frank Dehne (Carleton Univ.) Eduardo Rivera Campo (M xico) J rg-R diger Sack (Carleton Univ.) Godfried Toussaint (McGill Univ.) Jorge Urrutia (Univ. of Ottawa) (Chair) Sponsored by: Carleton University University of Ottawa Universit du Queb c Hull -------------------------------------------------------- REGISTRATION FORM Registration fee $ 60.00 Can Registration fee includes: Sunday reception, Wednesday informal reception, coffee breaks, and proceedings. Name: Affiliation: Address: Phone number: E-mail: PLEASE FILL OUT THE ABOVE REGISTRATION FORM AND MAIL WITH CHEQUE TO Second Canadian Conference in Computational Geometry c/o Jorge Urrutia Department of Computer Science University of Ottawa Ottawa, Canada K1N 9B4 Tel.: (613) 564-5447 E-mail: scccg@uot.csi2 FAX: (613) 564-5045 -------------------------------------------------------- PROGRAM All events, except Sunday reception and Wednesday informal reception are held at the University of Ottawa, Fateaux Hall. Sunday Evening, August 5, 1990 19:00 - Welcome Reception, 21:00 Novotel Hotel, Besserer Room. Monday, August 6, 1990 Room 147, Fateaux. 8:45 Opening Address 9:00 INVITED TALK, Franco Preparata (Univ. of Illinois at Urbana) 10:00-10:15 Break Session 1A, Room 147, Fateaux Point Sets 1 10:15 Maintaining the minimal distance of a point set in less than linear time. Michael Smid (Saarbr cken) 10:40 An optimal-time algorithm for ham-sandwich cuts in the plane. Chi-Yuan Lo (AT&T, Rutgers) and William Steiger (Rutgers) 11:05 Computing a point in the center of a point set in three dimensions. N. Naor (Tel-Aviv) and M. Sharir (Tel-Aviv, Courant) Session 1B, Room 135, Fateaux Implementation Issues 1 10:15 Geometry of bivariate splines. W. Whiteley (Champlain Regional College) 10:40 A unified linear-space approach to geometric mini- max problems. T. Asano (Osaka), M.E. Houle (Kyushu), H. Imai (Tokyo) and K. Imai (Tsuda College) 11:05 Accurate and efficient algorithms for proximity problems. P. Schorn (Z rich) 11:30-11:45 Break Session 2A, Room 147, Fateaux Point sets 2 11:45 Geometric clusterings. V. Capoyleas (Rutgers), G. Rote (Waterloo) and G. Woeginger (Graz) 12:10 Canonical cyclic orderings for point sets in the plane. A. Saalfeld (Bureau of the Census) Session 2B, Room 135, Fateaux Implementation Issues 2 11:45 Topology-oriented approach to robustness and its applications to several Voronoi-diagram algorithms. K. Sugihara, Y. Ooishi and T. Imai (Tokyo) 12:10 Rounding face lattices in d dimensions. V. Milenkovic (Harvard) 12:35 Lunch Session 3A, Room 147, Fateaux Separability 1 15:00 Separating bi-chromatic points by parallel lines. T. Asano, J. Hersenberg, J. Pach, E. Sontang, D. Souvaine and S. Suri 15:25 Separating convex sets on the plane. J. Czyzowicz (Hull), E. Rivera Campo (M xico), J. Urrutia (Ottawa) and J. Zaks (Haifa) 15:50 On the expected number of k-sets, I. B r ny (Hungary, Yale) and W. Steiger (Rutgers) Session 3B, Room 135, Fateaux Parallel Algorithms 15:00 An optimal parallel L1 metric Voronoi diagram algorithm. Y. C. Wee (Korea) and S. Chaiken (State Univ. of New York at Albany) 15:25 Efficient parallel algorithms on circular arcs. L. Chen (Ohio State Univ) 15:50 Decomposing the star graph into disjoint cycles. K. Qiu, H. Meijer and S. Akl (Queens Univ.) 16:15-16:30 Break Session 4A, Room 147, Fateaux Separability 2 16:30 Polygonal separators and digital shape recognition. B. Bhattacharya and T. Shermer (Simon Fraser) 16:55 A note on separation of plane convex sets. E. Rivera Campo (M xico) Session 4B, Room 135,Fateaux Stabbing 16:30 Good splitters with applications to ray shooting. R.B. Yeuda and S. Fogel (Technion, Haifa) 16:55 Maximal stabbing of segments in the plane. B. Jones and Y. Kee (Saskatchewan) Tuesday, August 7, 1990 9:00 INVITED TALK: Herbert Edelsbrunner (Univ. of Illinois at Urbana) 10:00-10:15 Break Session 5A, Room 147, Fateaux Motion Planning 1 10:15 Watchman routes under limited visibility. S. Ntafos (Texas) 10:40 Characterizing weak visibility polygons and related problems. S.K. Ghosh, A. Maheshwari (Bombay), S.P. Pal (Bangalore), S. Saluja and C.E.V. Madhavan (Bombay) 11:05 Improved combinatorial bounds and efficient techniques for certain motion planning problems with three degrees of freedom. D. Halperin (Courant) and M. Sharir (Courant, Tel- Aviv) Session 5B, Room 135, Fateaux Triangulations 1 10:15 Good triangulations in the plane. T. K. Dey (Purdue) 10:40 A robust parallel triangulation and shelling algorithm. I. Beichl and F. Sullivan (Natl. Inst. of Standards and Tech. Maryland) 11:15 Triangulating polygons with holes. R. Bar-Yeuda and R. Grinwald (Technion) 11:30-11:45 Break Session 6A, Room 147, Fateaux Motion Planning 2 11:45 Optimal motion of covisible points among obstacles in the plane. J.B. Mitchell and E. L. Wynters (Cornell) 12:10 On coordinate motion through a maze. J. Friedmann (Stanford), J. Hersenberg (DEC) and J. Snoeynik (Stanford) Session 6B, Room 135, Fateaux Triangulations 2 11:45 The atomic strain tensor. P.H. Mott, A.S. Argon (MIT) and U.W. Sutter (Z rich) 12:10 Barycentric triangulations of generalized maps. P. Lienhardt (Louis Pasteur Univ.) 12:35 Lunch Session 7A, Room 147, Fateaux Motion Planning and Order 15:00 Spherical orders, planar lattices and obstruction graphs. S. Foldes (Ecole Polytechnique, McGill) 15:25 Enumerating one-directional blocking relations and embedding them in small areas on the plane. W.P. Liu and I. Rival (Ottawa) 15:50 A new approach for drawing a hierarchical graph. P. Eades, X. Lin (Queensland) and R. Tamassia (Brown) Session 7B, Room 135,Fateaux Polygons 1 15:00 Dexterous rotations of polygons. D. Rus (Cornell) 15:25 Structure detection for polygon decomposition. M. Roussille, V. Bruy re and P. Dufour (Mons- Hainau, Belgium) 15:50 Monotone pieces of chains. V. Chandru (Purdue), V.T. Rajan (IBM Watson Res.) and R. Swaminathan (Purdue) 16:15-16:30 Break Session 8A, Room 147, Fateaux Motion Planning 3 16:30 Planar conflict resolution for air traffic control. Y. Chen, M. Hsieh (U.S. California), A. Inselberg(U.S. California, IBM) and H.Q. Lee (NASA) 16:55 Optimal polygon placement by translation. S.P. Pal, B. Dasgupta and C.E.V. Madhavan (Indian Inst. of Science) Session 8B, Room 135, Fateaux Implementation Issues 3 16:30 An object oriented workbench for experimental geometric computation. P. Schorn (Z rich) 16:55 Free-form surface modeling using implicit patches. B. Guo (Cornell) Wednesday, August 8, 1990 9:00 PROBLEM SESSION 10:00-10:15 Break Session 9A, Room 147, Fateaux Polygons 2 10:15 Visibility in finitely oriented polygons. V. Estivill-Castro and V. Rhaman (Waterloo) 10:40 An O(N log* N) time algorithm for covering simple polygons with squares. R. Bar-Yeuda and E. Ben-Chanoch (Technion) 11:05 Polyhedra: Faces are better than vertices. L. S. Heat, P.K. Paripaty and J.W. Roach (Virginia) Session 9B, Room 135, Fateaux Voronoi Diagrams 1 10:15 Finding constrained and weighted Voronoi diagrams in the plane. C.A. Wang (Memorial) and P.Y. Tsin (Windsor) 10:40 Fast algorithms for bounded Voronoi diagrams of restricted polygons. A. Lingas (Lund) 11:15 Voronoi diagrams over dynamic scenes. T. Ross (W rzburg) 11:30-11:45 Break Session 10A, Room 147, Fateaux Polygons 3 11:45 An efficient divide-and-conquer approximation algorithm for hyperrectangular partitions. T. Gonzalez, M. Razzazi (Santa Barbara) and Si- Qing Zheng (Louisiana) 12:10 On the complexity of shattering using arrangements. R. Freimer, J.S.B. Mitchel and C.D. Piatko (Cornell) Session 10B, Room 135, Fateaux Voronoi Diagrams 2 11:45 Voronoi diagrams coming from discrete groups on the plane. M.L. Maz n and T. Recio (Cantalabria) 12:10 Finding geodesic Voronoi diagrams of points in the presence of rectilinear barriers. Y.H. Tsin (Windsor) and C.A. Wang (Memorial) AFTERNOON FREE Evening Informal Reception. Time and place to be announced. Thursday, August 9, 1990 9:00 INVITED TALK: Selim Akl (Queen's University) 10:00-10:15 Break Session 11A, Room 147, Fateaux Visibility and Polygons 10:15 Minimal obscuring sets: the parallel view case. N. Mouaward (McGill) 10:40 Linear-time algorithms for weakly-monotone polygons. P.J. Hefferman (Cornell) 11:05 An algorithm for recognizing palm polygons. S. K. Ghosh, A. Maheshwari (TIFR, Bombay) and S. P. Pal and C.E.V. Madhavan (Bangalore) Session 11B, Room 135, Fateaux Convex Hulls 10:15 An algorithm to find the faces of the convex hull in higher dimensions. W.M. Stewart (New Brunswick) 10:40 Numerical stability of a convex hull algorithm for simple polygons. J.W. Jaromczyk and G.H. Wasilkowski (Kentucky) 11:15 Las Vegas gift-wrapping is twice as fast. R.A. Dwyer (North Carolina) 11:30-11:45 Break Session 12A, Room 147, Fateaux Visibility 11:45 Guarding convex sets on the plane. J. Czyzowicz (Hull), E. Rivera-Campo (Mexico), J. Urrutia (Ottawa) and J. Zaks (Haifa) 12:10 Optimum watchmen in spiral polygons. B.J. Nilsson (Lund) and D. Wood (Waterloo) Session 12B, Room 135, Fateaux Voronoi Diagrams 3 11:45 Dynamic Voronoi diagrams and Delaunay triangulations. C.L. Bajaj and W.J. Bouma (Purdue) 12:10 An on-line construction of higher order Voronoi diagrams and its randomized analysis. J.D. Boissonnat, O. Devillers and M. Teillaud (INRIA) 12:35 Lunch Session 13A, Room 147, Fateaux Ham-sandwich 15:00 Ham-sandwich sectioning of polygons. M. Diaz (Johns Hopkins) and J. O'Rourke (Smith College) 15:25 The convergence rate of the sandwich algorithm for approximating convex figures in the plane. G. Rote (Waterloo) 15:50 Cutting the volumes of convex polyhedra by a plane. I. Stojmenovic (Ottawa) Session 13B, Room 135,Fateaux Polygons 4 15:00 The complexity of minimum convex nested polyhedra. G. Das and D. Joseph (Wisconsin) 15:25 Constrained integer approximation to 2-d line intersections. S. Metha, M. Mukherjee and G. Nagy (Rensselaer) 15:50 Weighted 1-center problem in a simple polygon. S. Kabadi (New Brunswick), Y.P. Aneja (Windsor) and K.P.K. Nair (New Brunswick) 16:15-16:30 Break Session 14A, Room 147, Fateaux Steiner Trees 16:30 A reduced grid for rectilinear Steiner minimal trees. G.M. Shute (Minnesota) 16:55 Using partitioning and clustering techniques to generate rectilinear Steiner trees. L.L. Deneen and J.B. Dezell (Minnesota) Session 14B, Room 135, Fateaux Polygons 5 16:30 Circumscribing polygon of disjoint line segments. A. Mirzain (York) 16:55 Minimum polygon covers of parallel line segments. H. Meijer and D. Rappaport (Queen's) Friday, August 10, 1990 Session 15A, Room 147, Fateaux Visibility 1 9:00 Link length of rectilinear watchman tours in grids. E. Kranakis (Amsterdam), D. Krizank (Amsterdam, Rochester) and L. Meertens (Amsterdam) 9:25 Computing polygonal chords and the farthest visibility polygon. T.C. Kao and G.D. Knott (Maryland) 10:50 Shortest paths, visibility, and optimization in planar curvilinear objects. E.A. Melissaratos and D. Souvaine (New Brunswick) Session 15B, Room 135, Fateaux Implementations 9:00 An all round sweep algorithm for 2-dimensional nearest-neighbor problems. K. Hinrichs (Siegen), J. Nievergelt and P. Schorn (Z rich) 9:25 Algorithms for semi-on-line updates on decomposable problems. M. Smid (Saarlanders) 10:50 Testing geometric objects. K. Romanik and C. Smith (Maryland) 11:15-11:30 Break Session 16A, Room 147, Fateaux Visibility 2 11:30 Towards a general theory of visibility. S. Schuierer (Freiburg), G.J.E. Rawlins (Indiana) and D. Wood (Waterloo) 11:55 Minimum covers for grids and orthogonal polygons by periscope guards. L.P. Gewali (Nevada) and S. Ntafos (Texas) Session 16B, Room 135, Fateaux Circular arcs, TSP 11:30 Offsets of circular arc figures. S. Whitesides and R.Y. Zhao (McGill) 11:55 Tree traveling salesman problem. S.N. Kabadi (New Brunswick) and R. Chandrasekaran (Texas) 11:55-12:10 Break 12:10- INVITED TALK : Godfried Toussaint. 13:10 (McGill University) GENERAL INFORMATION REGISTRATION Please register in advance using the form provided. The conference registration and information desk will be in the Foyer of the Fateaux Hall at the University of Ottawa. It will be open as follows: August 6 8:30-12:00 and 15:00-17:00 August 7 8:30-12:00 August 8 8:30-12:00 The registration fee includes a copy of the proceedings, refreshments, Sunday and Wednesday receptions. ACCOMMODATION The following arrangements have been made for accommodation for participants to the Second Canadian Conference in Computational Geometry. Three accommodation choices are available to conference participants. 1) A block of 150 rooms has been reserved at the student residences at the University of Ottawa . 2) A block of 50 rooms has been reserved at the Journey's End Hotel, situated within three blocks of the University of Ottawa Campus, a five minute walk. 3) A block of 75 rooms has been reserved at the Novotel Hotel, also within three blocks of campus. The University of Ottawa Campus, the Journey's End and the Novotel are located at the heart of the downtown core of Ottawa. Participants wishing to take advantage of the attractions offered by our city will find the location of all of the lodging places offered ideal. The prices for accommodation ($CAN) (not including tax) are: 1) U. of O.: $28.35 (single); $37.80 (twin) 2) Journey's End: $70.88 (one person); $77.88 (two persons); $81.88 (three persons); $85.88 (four persons) 3) Novotel: $90.00 (single, double or twin), $105.00 (triple or quad) Deadline for reservations: The blocks of rooms will be held for the participants until the following dates: 1) U. of O.: July 15, 1990 2) Journey's End: July 15, 1990 3) Novotel: July 16, 1990 After these dates, reservations will depend on availability. Ottawa is a popular tourism center and during August all downtown hotels are very busy. We strongly advise you to reserve as soon as possible to avoid problems obtaining accommodation. Reservations must be arranged directly with the University or the hotel of your choice. Please be sure to mention that you are attending the Second Canadian Conference in Computational Geometry. (1) University of Ottawa: Please contact the residence office @ (613) 564-3463. (2) Journey's End: 290 Rideau Street, Ottawa, Ont, K1N 5Y3. Tels: 1-800-668-4200 and (613) 563-7511 (3) Novotel Ottawa: 33 Nicholas Street, Ottawa, Ont. K1N 9M7. Tels: 1-800-221-4542 and (613) 230-3033, FAX: (613) 230-7865 After this date, the rooms will be released and the regular rates will apply to available rooms. If you want to make other accommodation arrangements, some other downtown hotels are the Roxborough, 1-800-263-8967, $67 single/double; the Skyline, 1-800-268-1444, $120 single, $130 double; the Delta, 1-800-268-1133, $125 single, $140 double. Please confirm these rates directly with the hotels. Summer is also a popular camping time. The National Capital Commission, (613)-239-5000, has a campground at the Lebreton Flats, just 10 minutes walk from Parliament Hill. Numerous campgrounds are at the outskirts of Ottawa. For information call (613)-237-5158. TRANSPORTATION Ottawa International Airport on the south side of the city is served by Air Canada, Canadian Airlines International, KLM, Eastern, Pilgrim, City Express, First Air, and Wardair. An airport shuttle, running every 30 minutes, provides transportation to and from major hotels for about $6. A taxi to the University of Ottawa and the downtown area costs about $17. INFORMATION ABOUT OTTAWA The capital of Canada is a beautiful city with a metropolitan area of 850,000 people. It is located at the confluence of the Ottawa, Rideau and Gatineau rivers and the historic Rideau Canal. The Parliament Buildings stand on a cliff top overlooking the Ottawa River. The Peace Tower observation deck at 89.5 metres offers an excellent view of the Capital Region, including the Ottawa Valley and the Gatineau Hills to the north. In July and August the lawn of Parliament Hill is the scene of Changing the Guard at 10 a.m. and the Sound and Light show in the evening. The newly built Canadian Museum of Civilization and National Gallery of Canada are nearby. Other attractions available to visitors include the National Arts Centre, Supreme Court, National Museum of Natural Sciences, National Museum of Science and Technology, and National Aviation Museum. Many parkways crisscross the city and add to its warm and livable atmosphere. The University of Ottawa is located in downtown Ottawa along the east bank of the Rideau Canal. There are many places of interest within walking distance of the campus, including Parliament Hill, the National Gallery of Canada, the Currency Museum, the War Museum, and the National Arts Centre, to name but a few. Nearby is the Byward Market where a range of restaurants sure to satisfy any taste and budget can be found. Evening entertainment can be found not only in the Market, but also in downtown Hull, Qu bec (a fifteen minute walk from the Byward Market across the Alexandra Bridge over the Ottawa River ). The weather in the middle of August is usually warm, with the average minimum 17oC and average maximum 26oC. Occasional rain is possible.