C is a general-purpose programming language. It has been closely associated with the UNIX operating system where it was developed, since both the system and most of the programs that run on it are written in C. The language, however, is not tied to any one operating system or machine; and although it has been called a ‘‘system programming language’’ because it is useful for writing compilers and operating systems, it has been used equally well to write major programs in many different domains. Many of the important ideas of C stem from the language BCPL, developed by Martin Richards. The influence of BCPL on C proceeded indirectly through the language B, which was written by Ken Thompson in 1970 for the first UNIX system on the DEC PDP-7. BCPL and B are ‘‘typeless’’ languages. By contrast, C provides a variety of data types. The fundamental types are characters, and integers and floating point numbers of several sizes. In addition, there is a hierarchy of derived data types created with pointers, arrays, structures and unions. Expressions are formed from operators and operands; any expression, including an assignment or a function call, can be a statement. Pointers provide for machine-independent address arithmetic. C provides the fundamental control-flow constructions required for well-structured programs: statement grouping, decision making (if-else), selecting one of a set of possible values (switch), looping with the termination test at the top (while, for) or at the bottom (do), and early loop exit (break). Functions may return values of basic types, structures, unions, or pointers. Any function may be called recursively. Local variables are typically ‘‘automatic’’, or created anew with each invocation. Function definitions may not be nested but variables may be declared in a block-structured fashion. The functions of a C program may exist in separate source files that are compiled separately. Variables may be internal to a function, external but known only within a single source file, or visible to the entire program.

This paper describes the results of a 500 million packet trace of a popular on-line, multi-player, game server. The results show that the traffic behavior of this heavily loaded game server is highly predictable and can be attributed to the fact that current game designs target the saturation of the narrowest, last-mile link. Specifically, in order to maximize the interactivity of the game and to provide relatively uniform experiences between all players, on-line games typically fix their usage requirements in such a way as to saturate the network link of their lowest speed players. While the traffic observed is highly predictable, the trace also indicates that these on-line games provide significant challenges to current network infrastructure. Due to synchronous game logic requiring an extreme amount of interactivity, a close look at the trace reveals the presence of large, highly periodic, bursts of small packets. With such stringent demands on interactivity, routers must be designed with enough capacity to quickly route such bursts without delay. As current routers are designed for bulk data transfers with larger packets, a significant, concentrated deployment of online game servers will have the potential for overwhelming current networking equipment.

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The Held-Karp (HK) lower bound is the solution to the linear programming relaxation of the standard integer programming formulation of the traveling salesman problem (TSP). For numbers of cities N up to 30,000 or more it can be computed exactly using the Simplex method and appropriate separation algorithms, and for N up to a million good approximations can be obtained via iterative Lagrangean relaxation techniques first suggested by Held and Karp. In this paper, we consider three applications of our ability to compute/approximate this bound. First, we provide empirical evidence in support of using the HK bound as a stand-in for the optimal tour length when evaluating the quality of near-optimal tours. We show that for a wide variety of randomly generated instance types the optimal tour length averages less than 0.8% over the HK bound, and even for the real-world instances in TSPLIB the gap is almost always less than 2%. Moreover, our data indicates that the HK bound can provide substa...

Grounded theory methods of Strauss and Corbin (1990) and multidimensional scaling techniques (Kruskal & Wish, 1991) were used in this investigation to study the factors that influence a woman's choice to remain in or to leave a male-dominated major (Zuckerman, 1981). Focus group interviews were conducted with 62 sophomore women who had originally chosen male-dominated majors as freshmen to gain insight into the meanings and motivations of the student decisions. The participants responded to a 25-item survey which yielded a-three dimension solution with five clusters in the multidimensional scaling analysis. Five themes emerged from the focus groups as factors influencing a woman's choice to remain in or to leave a male-dominated major: (a) self confidence and refuse to lose attitude; (b) interest in the field; (c) career goals, jobs, and money; (d) ability and experience in the field; and (e) the desire to make a difference. The three dimensions were (a) time of experience, (b) motivation, and (c) career rewards. The five clusters were: (a) pre-college experiences, (b) college experiences, (c) career rewards, (d) self-confidence, and (e) selffulfillment.

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This research applies formal methods in logic, verification, and synthesis to digital design engineering. The work centers on the use of applicative notation for system description and functional algebras for design development. The general goal is to develop a comprehensive methodology for constructing correct hardware

This paper introduces the issues of portability for C applications between Unix variants, including semantic differences in libraries and system calls, API support and reasonable minimum platform requirements. It also describes the approach used by Portable OpenSSH to the problems of secure portability and points to some areas where more work is needed by platform vendors. 1