Vertex-disjoint quadrilaterals in graphs Original Research Article

Let image be a positive integer and image a graph of order image. In (Discrete Math. 203 (1999) 229), we proved that if image and image then image contains image vertex-disjoint quadrilaterals. In this paper, we investigate vertex-disjoint quadrilaterals in image with image, and we have found the best minimum degree condition image such that image contains image vertex-disjoint quadrilaterals. As a result of our method, we have improved our previous result as follows: If image and image then image contains image vertex-disjoint quadrilaterals.