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51.
本文提供了一种检测操作系统中死锁的方法.该方法包含三个步骤:(1)通过检测进程加锁与解锁是否匹配来获得锁的持有者;(2)从异常进程中筛选出锁的等待者;(3)通过检查锁的持有者与等待者是否会形成循环等待图来判定死锁.通过实验发现,该方法对系统性能的影响小于l%,而且不需要修改内核源码和源程序. 相似文献
52.
A multi-secret sharing scheme is a protocol to share m arbitrarily related secrets s1, … , sm among a set of n participants. In this paper, we propose an ideal linear multi-secret sharing scheme, based on monotone span programs, where each subset of the set of participants may have the associated secret. Our scheme can be used to meet the security requirement in practical applications, such as secure group communication and privacy preserving data mining etc. We also prove that our proposed scheme satisfies the definition of a perfect multi-secret sharing scheme. 相似文献
53.
54.
Ana Gàl 《Computational Complexity》2001,10(4):277-296
We give a characterization of span program size by a
combinatorial-algebraic measure. The measure we consider is a generalization
of a measure on covers which has been used to prove lower
bounds on formula size and has also been studied with respect to communication
complexity.?In the monotone case our new methods yield lower bounds for
the monotone span program complexity of explicit Boolean functions in
n variables over arbitrary fields, improving the previous lower bounds
on monotone span program size. Our characterization of span program
size implies that any matrix with superpolynomial separation between
its rank and cover number can be used to obtain superpolynomial lower
bounds on monotone span program size. We also identify a property
of bipartite graphs that is suficient for constructing Boolean functions
with large monotone span program complexity.
Received: September 30, 2000. 相似文献
55.
The aim of this paper is to extend the probabilistic choice in probabilistic programs to sub-probabilistic choice, i.e., of
the form (p)P
⋈(q)Q where p + q ⩽ 1. It means that program P is executed with probability p and program Q is executed with probability q. Then, starting from an initial state, the execution of a sub-probabilistic program results in a sub-probability distribution.
This paper presents two equivalent semantics for a sub-probabilistic while-programming language. One of these interprets programs as sub-probabilistic distributions on state spaces via denotational
semantics. The other interprets programs as bounded expectation transformers via wp-semantics. This paper proposes an axiomatic systems for total logic, and proves its soundness and completeness in a classical
pattern on the structure of programs. 相似文献
56.
递归程序设计的公式化方法 总被引:3,自引:0,他引:3
如果在设计递归程序时首先写出它的递归公式,那么编码过程会大大简化,而且得到的程序具有极好的可读性。这一思想有助于递归程序的标准化,并具有很大的普遍性。 相似文献
57.
一种基于程序正确性证明理论的程序开发方法 总被引:3,自引:0,他引:3
程序的形式推导方法是一种基于程序正确性证明理论的程序开发方法,它使得程序的开发和证明同时进行,程序开发完成的同时其正确性亦得以保 证,以两个问题的程序开发为例说明了程序的形式推导方法的使用。 相似文献
58.
We show that linear-time self-interpretation of the pure untyped lambda calculus is possible, in the sense that interpretation has a constant overhead compared to direct execution under various execution models. The present paper shows this result for reduction to weak head normal form under call-by-name, call-by-value and call-by-need.We use a self-interpreter based on previous work on self-interpretation and partial evaluation of the pure untyped lambda calculus.We use operational semantics to define each reduction strategy. For each of these we show a simulation lemma that states that each inference step in the evaluation of a term by the operational semantics is simulated by a sequence of steps in evaluation of the self-interpreter applied to the term (using the same operational semantics).By assigning costs to the inference rules in the operational semantics, we can compare the cost of normal evaluation and self-interpretation. Three different cost-measures are used: number of beta-reductions, cost of a substitution-based implementation (similar to graph reduction) and cost of an environment-based implementation.For call-by-need we use a non-deterministic semantics, which simplifies the proof considerably. 相似文献
59.
Goodyear Rodney K.; Abadie Philip D.; Walsh W. Bruce 《Canadian Metallurgical Quarterly》1983,30(2):283
Examined the graduate school origins of authors of Journal of Counseling Psychology (JCP) articles in Volumes 15–28 to extend a previous analysis of Volumes 1–24 by the 3rd author et al (1969). Comparisons of the 2 14-yr periods reveal that some universities retained the same or similar ranks across both periods, some declined in importance as sources of authors, and others emerged as major sources of JCP authors. (6 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
60.