The crossing number cr(G) of a graph G is the minimum number of crossings in a nondegenerate planar drawing of G. The rectilinear crossing number cr(G) of G is the minimum number of crossings in a rectilinear nondegenerate planar drawing (with edges as straight line segments) of G. Zarankiewicz proved in 1952 that cr(Kn1,n2) ≤ Z(n1, n2) := ⌊ n1 2 ⌋ ⌊ n1−1 2 ⌋ ⌊ n2 2 ⌋ ⌊ n2−1 2 ⌋ . We define an ...

Abstract The Zarankiewicz problem asks for an estimate on z ( m , n ; s t ), the largest number of 1’s in × matrix with all entries 0 or 1 containing no submatrix consisting entirely 1’s. We show that a classical upper bound ) due to Kővári, Sós and Turán is tight up constant broad range parameters. proof relies new quantitative variant random algebraic method.

There exist some Drawing for any graph G = (V,E) on plan. An important aim in Graph Theory and Computer science is obtained a best drawing of an arbitrary graph. Also, a draw of a non-planar graph G on plan generate several edge-cross. A good drawing (or strongly best drawing) of G is consist of minimum edge-cross. The crossing number of a graph G, is the minimum number of crossings in a drawin...

The crossing number cr(G) of a graph G is the minimum number of crossings in a nondegenerate planar drawing of G. The rectilinear crossing number cr(G) of G is the minimum number of crossings in a rectilinear nondegenerate planar drawing (with edges as straight line segments) of G. Zarankiewicz proved in 1952 that cr(Kn1,n2) ≤ Z(n1, n2) := ⌊ n1 2 ⌋ ⌊ n1−1 2 ⌋ ⌊ n2 2 ⌋ ⌊ n2−1 2 ⌋ . We define an ...

We consider the minimum number of zeroes in a 2m 2n (0; 1)-matrix M that contains no m n submatrix of ones. We show that this number, denoted by f(m; n), is at least 2n + m + 1 for m n. We determine exactly when this bound is sharp and determine the extremal matrices in these cases. For any m, the bound is sharp for n = m and for all but nitely many n > m. A general upper bound due to Gentry, f...

Consider the minimum number f(m,n) of zeroes in a 2m×2n (0, 1)-matrixM that contains no m×n submatrix of ones. This special case of the well-known Zarankiewicz problem was studied by Griggs and Ouyang, who showed, for m ≤ n, that 2n+m+1 ≤ f(m,n) ≤ 2n + 2m − gcd(m,n) + 1. The lower bound is sharp when m is fixed for all large n. They proposed determining limm→∞{f(m,m+ 1)/m}. In this paper, we sh...

3 Third Lecture 11 3.1 Applications of the Zarankiewicz Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 The Turán Problem for Trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.3 The Girth Problem and Moore’s Bound . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.4 Application of Moore’s Bound to Graph Spanners . . . . . . . . . . . ....