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Unformatted text preview: $$ FETCH Cl ; /* Will cause one tuple to be assigned t o the structure Cl * / DO WHILE (STATUS = 0) ; PUT SKIP(2) LIST( Cl .PNAME, C1 .SALARY) ; SAL = SAL + SALARY ; COUNT = COUNT +1 ; $$ FETCH Cl ; END ; PUT SKIP(2) LIST('Average Salary i s SAL/COUNT) ; The WVU DBMS executes on the VAX lin e of computers running VMS . The WVU DBMS i s available at no cost to any academi c institution that wishes to use it . Th e User's Guide and complete syntax as well a s instructions for acquiring the software can be obtained by writing : John Atkins Department of Statistic s and Computer Science 305 Knapp Hal l West Virginia Universit y Morgantown, W .Va . 2650 6 REFERENCE S 1. Atkins, J .M., and D .M. Henry , "A Database Management Syste m Project for an Undergraduate Databas e Design Course," Proceedings of the 1985 ACM Annual Conference, 1985 , pp . 266-27 0 2. Stout, Quentin F . and Patricia A . Woodworth, "Relational Databases, " The American Mathematical Monthly, February , 1983, Vol .90, No . 2, pp . 101-11 8 3. Ullman, Jeffrey D ., Principles o f Database and Knowledge-Base Systems , Volume 1, Computer Science Press, 198 8 * k * * * * k * * * * * * * * * * * * i k * J e * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * , F * * * * * * * * * * ,t* ********* * DINING PHILOSPHERS--- continued from page 2 4 ing line after thinking and before eating even if neither o f his neighbors is eating . Starvation would mean that som e hungry philosopher stays in the waiting line forever . T h e solution guarantees that whatever hungry philosopher P i s first in line is waiting for at least, one of his two neighbor s to complete his clinker, This n n is t . happen within 7' tim e units, at which time P begins to eat and is removed fro m the waiting line . All other waiting philosophers move on e step closer to the beginning of the line . Thus P w ill hav e to wait at most 3T time units before beginning to eat an d starvation is precluded . Maximal Efficiency : The solution achieves maximal effi- ciency since only those philosophers who are neighbors of th e p h ilo so p h er at th e h ead o f th e w aitin g lin e are co n strain ed [4 ] from beginning to eat by the solution's control protocol . Maximal efficiency does not allow the situation where on e philosopher dines while the rest wait to cat . This canno t happen in this solution since at most one neighbor of th e head philosopher can be the solitary dining philosopher . I f the solitary dining philosopher is not a neighbor of the hea d philosopher, the head philosopher may proceed to cat sinc e his neighbors are not eating . If the solitary dining philoso- pher is a neighbor of the head philosopher, tlren the on e philosopher who is a non-neighbor of both the head philoso- pher and the solitary dining philosopher may begin to eat ....
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- Winter '11