Results 11  20
of
271
On The Sample Complexity Of PacLearning Using Random And Chosen Examples
 IN PROCEEDINGS OF THE 1990 WORKSHOP ON COMPUTATIONAL LEARNING THEORY
, 1991
"... Two protocols used for learning under the paclearning model introduced by Valiant are learning from random examples and learning from membership queries. Membership queries have also been used to efficiently and exactly learn a concept class that is too difficult to paclearn using random examples. ..."
Abstract

Cited by 26 (0 self)
 Add to MetaCart
(Show Context)
Two protocols used for learning under the paclearning model introduced by Valiant are learning from random examples and learning from membership queries. Membership queries have also been used to efficiently and exactly learn a concept class that is too difficult to paclearn using random examples. We ask whether using membership queries in conjunction with or instead of random examples serve a new purpose: helping to reduce the total number of examples needed to paclearn a concept class C already known to be paclearnable using just random examples. We focus on concept classes that are dense in themselves, such as haftspaces of R ', rectangles in the plane, and the class Z = {[0, a]: 0 _ a < 1} of initial segments of [0, 1]. The main
Symmetry Breaking in Graphs
 Electronic Journal of Combinatorics
, 1996
"... A labeling of the vertices of a graph G, OE : V (G) ! f1; : : : ; rg, is said to be rdistinguishing provided no automorphism of the graph preserves all of the vertex labels. The distinguishing number of a graph G, denoted by D(G), is the minimum r such that G has an rdistinguishing labeling. T ..."
Abstract

Cited by 23 (4 self)
 Add to MetaCart
(Show Context)
A labeling of the vertices of a graph G, OE : V (G) ! f1; : : : ; rg, is said to be rdistinguishing provided no automorphism of the graph preserves all of the vertex labels. The distinguishing number of a graph G, denoted by D(G), is the minimum r such that G has an rdistinguishing labeling. The distinguishing number of the complete graph on t vertices is t. In contrast, we prove (i) given any group \Gamma, there is a graph G such that Aut(G) = \Gamma and D(G) = 2; (ii) D(G) = O(log(jAut(G)j)); (iii) if Aut(G) is abelian, then D(G) 2; (iv) if Aut(G) is dihedral, then D(G) 3; and (v) If Aut(G) = S 4 , then either D(G) = 2 or D(G) = 4. Mathematics Subject Classification 05C,20B,20F,68R 1
The Cell Structures of Certain Lattices
, 1991
"... . The most important lattices in Euclidean space of dimension n 8 are the lattices A n (n ³ 2), D n (n ³ 4), E n (n = 6 , 7 , 8) and their duals. In this paper we determine the cell structures of all these lattices and their Voronoi and Delaunay polytopes in a uniform manner. The results for E 6 * ..."
Abstract

Cited by 19 (8 self)
 Add to MetaCart
(Show Context)
. The most important lattices in Euclidean space of dimension n 8 are the lattices A n (n ³ 2), D n (n ³ 4), E n (n = 6 , 7 , 8) and their duals. In this paper we determine the cell structures of all these lattices and their Voronoi and Delaunay polytopes in a uniform manner. The results for E 6 * and E 7 * simplify recent work of Worley, and also provide what may be new spacefilling polytopes in dimensions 6 and 7. 1. Introduction The CoxeterDynkin diagrams of types A n , D n , E 6 , E 7 and E 8 arise in surprisingly different parts of mathematics  see the discussions by Arnold [1] and Hazewinkel et al. [30]. In the present paper we study __________________ * This paper appeared in {\m Miscellanea mathematica}, P. Hilton, F. Hirzebruch, and R. Remmert, Eds., SpringerVerlag, NY, 1991, pp. 71107. (**) From the English version AutodaFe(Continuum, New York, p. 385) as translated by C. V. Wedgwood: "You have but to know an object by its proper name for it to lose its dange...
Drawing Stressed Planar Graphs in Three Dimensions
 In
, 1995
"... There is much current interest among researchers to find algorithms that will draw graphs in three dimensions. It is well known that every 3connected planar graph can be represented as a strictly convex polyhedron. However, no practical algorithms exist to draw a general 3connected planar graph as ..."
Abstract

Cited by 18 (0 self)
 Add to MetaCart
(Show Context)
There is much current interest among researchers to find algorithms that will draw graphs in three dimensions. It is well known that every 3connected planar graph can be represented as a strictly convex polyhedron. However, no practical algorithms exist to draw a general 3connected planar graph as a convex polyhedron. In this paper we review the concept of a stressed graph and how it relates to convex polyhedra; we present a practical algorithm that uses stressed graphs to draw 3connected planar graphs as strictly convex polyhedra; and show some examples. Key words: graph, stressed graph, convex polyhedron, reciprocal polyhedron 1 Introduction It is well known that 3connected planar graphs can be drawn as convex polyhedra. However, no practical algorithms exist to draw general 3connected planar graphs as convex polyhedra. The twodimensional (2D) drawing in Figure 1 is 3connected and planar, and the corresponding polyhedron is drawn in Figure 2 as three different views. The 2D ...
The combinatorics of frieze patterns and Markoff numbers
, 2007
"... ... model based on perfect matchings that explains the symmetries of the numerical arrays that Conway and Coxeter dubbed frieze patterns. This matchings model is a combinatorial interpretation of Fomin and Zelevinsky’s cluster algebras of type A. One can derive from the matchings model an enumerativ ..."
Abstract

Cited by 17 (1 self)
 Add to MetaCart
... model based on perfect matchings that explains the symmetries of the numerical arrays that Conway and Coxeter dubbed frieze patterns. This matchings model is a combinatorial interpretation of Fomin and Zelevinsky’s cluster algebras of type A. One can derive from the matchings model an enumerative meaning for the Markoff numbers, and prove that the associated Laurent polynomials have positive coefficients as was conjectured (much more generally) by Fomin and Zelevinsky. Most of this research was conducted under the auspices of REACH (Research Experiences in Algebraic Combinatorics at Harvard).
Multitriangulations as complexes of star polygons
, 2007
"... Maximal (k+1)crossingfree graphs on a planar point set in convex position, that is, ktriangulations, have received attention in recent literature, with motivation coming from several interpretations of them. We introduce a new way of looking at ktriangulations, namely as complexes of star poly ..."
Abstract

Cited by 17 (7 self)
 Add to MetaCart
Maximal (k+1)crossingfree graphs on a planar point set in convex position, that is, ktriangulations, have received attention in recent literature, with motivation coming from several interpretations of them. We introduce a new way of looking at ktriangulations, namely as complexes of star polygons. With this tool we give new, direct, proofs of the fundamental properties of ktriangulations, as well as some new results. This interpretation also opensup new avenues of research, that we briefly explore in the last section.