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1.
Given any [c], [a], [d] xxxxxxxxR/M such that [d] ≤ [a] ≤ [c], [a] is locally noncuppable between [c] and [d] if [d] < [a] ≤ [c] and [a] ∨ [b] < [c] for any [b] xxxxxxxxR/M such that [d] ≤ [b] < [c]. It will be shown that given any nonzero [c] xxxxxxxxR/M, there are [a], [d] xxxxxxxxR/M such that [d] < [a] ≤ [c] and [a] is locally noncuppable between [c] and [d]. 相似文献
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张再跃 《计算机科学技术学报》2001,16(1):0-0
In the study of cappable and noncappable properties of the recursively enumerable(r.e.)degrees.Lempp suggested a conjecture which asserts that for all r.e.degrees and b,if a ≮b then there exists an r.e.degree c such that c≤a and c≮b and c is cappable.We shall prove in this paper that this conjecture holds under the condition that a is high.Working below a high r.e.degree h,we show that for any r.e.degree b with h≮b,there exist r.e.degrees a0 and a1 and such that a0,a1≮b,a0,a1≤h,and a0 and a1 from a minimal pair. 相似文献
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An r.e. degree c is contiguous if degwtt(A)=degwtt(B)for any r.e. sets A,B∈c.In this paper,we generalize the notation of contiguity to the structure R/M, the upper semilattice of the r.e. degree set R modulo the cappable r.e. degree set M.An element[C]∈R/M is contiguous if s[degwtt(A)]=[degwtt(B)]for any r.e. sets A,B such that degT(A),degT(B)∈[c],It is proved in this paper that every nonzero element in R/M is not contiguous,i.e.,for every element [C]∈R/M,if[C]≠[O] then there exist at least two r.e. sets A,B such that degT(A),degT(B)∈[C]and [degwtt[A]≠[degwtt(B)]. 相似文献
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Li Jianzhong 《计算机科学技术学报》1992,7(4):316-327
In order to reduce the disk access time,a database can be stored on several simultaneously accessible disks.In this paper,we are concerned with the dynamic d-attribute database allocation problem for range queries,An allocation method,called coordinate moule allocation method,is proposed to allocate data in a d-attribute database among disks so that the maximum disk accessing concurrency can be achieved for range queries.Our analysis and experiments show that the method achieves the optimum or near-optimum parallelism for range queries.The paper offers the conditions under which the method is optimal .The worst case bounds of the performance of the method are also given.In addition,the parallel algorithm of processing range queries in described at the end of the paper.The method has been used in the statistic and scientific database management system whic is being designed by us. 相似文献
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Sui Yuefei 《计算机科学技术学报》1993,8(3):15-18
A new reducibility between the recursive sets is defined,which is appropriate to be used in the study of th polynomial reducibility and the NP-problem. 相似文献
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该文证明了在 Rwtt/ Mwtt中除了最大元和最小元外 ,每个元 c是枝点元素 ,即为某两个大于 c的元素的最大下界 ,其中 Rwtt/ Mwtt是递归可枚举弱真值表归约度集 Rwtt模可盖递归可枚举弱真值表归约度集 Mwtt的商 相似文献
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基于量子逻辑的自动机理论是量子计算模型的一个重要研究方向.该文研究了基于量子逻辑的图灵机(简称量子图灵机)及其一些变形,给出了包括非确定型量子图灵机l-VTM,确定型量子图灵机l-VDTM以及相应类型的多带量子图灵机,并引入量子图灵机基于深度优先与宽度优先识别语言的两种不同定义方式,证明了这两种定义方式在量子逻辑意义下是不等价的.进一步证明了l-VTM、l-VDTM与相应类型的多带量子图灵机之间的等价性.其次,给出了量子递归可枚举语言及量子递归语言的定义,并给出了二者的层次刻画,证明了l-VTM与l-VDTM不等价,但两者作为量子递归语言的识别器是等价的.最后,文中讨论了基于量子逻辑的通用图灵机的存在性问题,给出了一套合理编码系统,证明了基于量子逻辑的通用图灵机在其所取值的正交模格无限时不存在,而在其所取值的正交模格有限时是存在的. 相似文献
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LI Angsheng & ZHAO Yicheng . Institute of Software Chinese Academy of Sciences Beijing China . School of Information Sciences Beijing Normal University Beijing China 《中国科学F辑(英文版)》2004,47(5):635-654
~~Plus cupping degrees do not form an ideal~~ 相似文献
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证明存在递归可枚举图灵度a和c使得ca,并且对每个递归可枚举图灵度b≤Ta, b≠c, 其中a是R/M中的一个元素,R/M是递归可枚举图灵度集R模可盖图灵度集M的商. 相似文献
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Csuhaj-Varjú Erzsébet Martín-Vide Carlos Păaun Gheorgh Salomaa Arto 《Natural computing》2003,2(3):299-318
Watson-Crick L systems are language generating devices making use ofWatson-Crick complementarity, a fundamental concept of DNA computing.These devices are Lindenmayer systems enriched with a trigger forcomplementarity transition: if a ``bad' string is obtained, then thederivation continues with its complement which is always a ``good'string. Membrane systems or P systems are distributed parallel computingmodels which were abstracted from the structure and the way offunctioning of living cells. In this paper, we first interpret theresults known about the computational completeness of Watson-Crick E0Lsystems in terms of membrane systems, then we introduce a related way ofcontrolling the evolution in P systems, by using the triggers not in theoperational manner (i.e., turning to the complement in a ``bad'configuration), but in a ``Darwinian' sense: if a ``bad' configurationis reached, then the system ``dies', that is, no result is obtained.The triggers (actually, the checkers) are given as finite state multisetautomata. We investigate the computational power of these P systems.Their computational completeness is proved, even for systems withnon-cooperative rules, working in the non-synchronized way, andcontrolled by only two finite state checkers; if the systems work in thesynchronized mode, then one checker for each system suffices to obtainthe computational completeness. 相似文献
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证明存在递归可枚举图灵度a和c使得c(≤)a,并且对每个递归可枚举图灵度b≤Ta, b≠c, 其中a是R/M中的一个元素,R/M是递归可枚举图灵度集R模可盖图灵度集M的商. 相似文献
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Approximation and universality of fuzzy Turing machines 总被引:1,自引:1,他引:1
LI YongMing College of Computer Science Shaanxi Normal University Xi’an China 《中国科学F辑(英文版)》2008,51(10):1445-1465
Fuzzy Turing machines are the formal models of fuzzy algorithms or fuzzy computations. In this paper we give several different formulations of fuzzy Turing machine, which correspond to nondeterministic fuzzy Turing machine using max-* composition for some t-norm* (or NFTM*, for short), nondeterministic fuzzy Turing machine (or NFTM), deterministic fuzzy Turing machine (or DFTM), and multi-tape versions of fuzzy Turing machines. Some distinct results compared to those of ordinary Turing machines are obtained. First, it is shown that NFTM*, NFTM, and DFTM are not necessarily equivalent in the power of recognizing fuzzy languages if the t-norm* does not satisfy finite generated condition, but are equivalent in the approximation sense. That is to say, we can approximate an NFTM* by some NFTM with any given accuracy; the related constructions are also presented. The level characterization of fuzzy recursively enumerable languages and fuzzy recursive languages are exploited by ordinary r.e. languages and recursive languages. Second, we show that universal fuzzy Turing machine exists in the approximated sense. There is a universal fuzzy Turing machine that can simulate any NFTM* on it with a given accuracy. 相似文献
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Newly emerging portable multimedia systems demand low-energy processing. Until now, however, designers of microprocessors for PCs and engineering workstations have focused mostly on high speed. Microcontroller designers, on the other hand, have taken low power dissipation as a first priority. Today's portable multimedia system design calls for developers to combine these two approaches, lowering power consumption while maintaining reasonable performance. There are several approaches to reducing power dissipation. Using advanced process technology is one of them. Another approach merges a DRAM with a high-performance RISC processor on a single silicon chip-what we call embedded DRAM, or eRAM. This is exactly the concept that this new processor, M32R/D, embodies 相似文献