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List partitions generalize list colourings and list homomorphisms. Each symmetric matrix M over 0; 1; deenes a list partition problem. Diierent choices of the matrix M lead to many well-known graph the-oretic problems including the problem of recognizing split graphs and their generalizations, nding homogeneous sets, joins, clique cutsets, stable cutsets,(More)
We introduce a parametrized family of graph problems that includes several well-known graph partition problems as special cases. We develop tools which allow us to classify the complexity of many problems in this family, and in particular lead us to a complete classiication for small values of the parameters. Along the way, we obtain a variety of speciic(More)
Burkitt's lymphoma (BL) represents a high malignant B cell tumour. It has been proposed that cytokines are responsible for some of the characteristics of BL. We have analysed a panel of different BL and lymphoblastoid cell lines (LCLs) for the expression of cytokines, including: IL 1 alpha, IL 1 beta, IL2, IL3, IL4, IL6, IL8, IL10, TNF alpha and TNF beta(More)
We consider the following generalization of split graphs: A graph is said to be a (k, ℓ)-graph if its vertex set can be partitioned into k independent sets and ℓ cliques. (Split graphs are obtained by setting k = l = 1). Much of the appeal of split graphs is due to the fact that they are chordal, a property not shared by (k, ℓ)-graphs in general. (For(More)
A skew partition as defined by Chvátal is a partition of the vertex set of a graph into four nonempty parts AA BB CC D such that there are all possible edges between A and B and no edges between C and D. We present a polynomial-time algorithm for testing whether a graph admits a skew partition. Our algorithm solves the more general list skew partition(More)
The production of cytokines was analysed in Hodgkin's disease (HD) derived cell lines by enzyme linked immunosorbent tests (ELISA) and Northern blot experiments. Our results demonstrate that HD derived cell lines produce a variety of cytokines, such as IL1 alpha, IL4, IL5, IL6, IL8, TNF alpha, TNF beta and GM-CSF but not IL1 beta, IL2, IL3 and G-CSF. In(More)
A homogeneous set is a non-trivial module of a graph, i.e. a non-empty, non-unitary, proper subset of a graph's vertices such that all its elements present exactly the same outer neighborhood. Given two published an all-fast O(n 2 2) algorithm which was recently proven wrong [5], so that the HSSP's known upper bound would have been reset thereafter at(More)