A graph is a split graph if its vertices can be partitioned into a clique and a stable set. A graph is a k-split graph if its vertices can be partitioned into k sets, each of which induces a split graph. We show that the strong perfect graph conjecture is true for 2-split graphs and we design a polynomial algorithm to recognize a perfect 2-split graph.

The scratching of pen against paper signaled something at once mundane and momentous. “What is your name, your age, your residence?” asked Harvey Risk, a representative of the Southern Claims Commission. “My name is Mary Blackburn.... My age is about forty-fi ve years. My residence near Middlebrook,” the claimant responded. The commission awarded compensation for property losses during the Amer...

In this paper we propose an architecture for using crossorganization information sharing to identify members of a group of hosts enslaved for malicious purposes on the Internet. We root our system in so-called “detectives”— savvy network monitors like sophisticated intrusion detection systems or honeyfarms that have a deep understanding of malicious behavior. We augment information from these d...

The enforced migration of Africans to the Americas in conditions of slavery lasted from the middle of the sixteenth century until the 1860s and constituted the largest movement of people across the Atlantic until the middle of the nineteenth century. Referred to as the notorious “Middle Passage” because of the terrible conditions on board slave ships, this migration involved at least 12 million...

It is difficult to make sweeping statements about the status of women during the first century because there were exceptions to any characterization that might be made. However, there were laws, widely accepted codes, and assumptions regarding roles of women. These provide insight into the sort of life women lived during this period. As might be expected, there was a wide range of lifestyles fo...

Some years ago Vignati (refs. 1, 2, 3) showed that, under some particular circumstances (inter alia : isobaric processes connected through internal heat exchangers), the efficiency of an Ericsson cycle involving a real gas can exceed the Carnot limit ηC , in contradiction with the second principle of thermodynamics. However, the convergence of Vignati’s algorithm, giving the temperature differe...

Partition functions Z(x) of statistical mechanics are generally approximated by integrals. The approximation fails in small cavities or at very low temperature, when the ratio x between the energy quantum and thermal energy is larger or equal to unity. In addition, the exact calculation, which is based on number theoretical concepts, shows excess low frequency noise in thermodynamical quantitie...

A practical method is presented that permits retrieval from a table in constant time. The method is suitable for large tables and consumes, in practice, O(n) space for n table elements. In addition, the table and the hashing function can be constructed in O(n) expected time. Variations of the method that offer different compromises between storage usage and update time are presented.

Americans are immigrants—people whose origins are various but whose destinies made them American. Immigration—voluntary or involuntary—is what created all multiracial and multicultural nations. The United States is a prime example. Sometimes the migrants moved freely from the area of origin to the area of destination. Such was the experience of the European immigrants. Sometimes their movement ...

An ordered minimal perfect hash table is one in which no collisions occur among a prede ned set of keys, no space is unused and the data are placed in the table in order. A new method for creating ordered minimal perfect hash functions is presented. It creates hash functions with representation space requirements closer to the theoretical lower bound than previous methods. The method presented ...