共查询到20条相似文献,搜索用时 15 毫秒
1.
Tarek Sayed Ahmed 《Mathematical Logic Quarterly》2009,55(6):666-668
We show that certain properties of dimension complemented cylindric algebras, concerning neat embeddings, do not generalize much further. Let α ≥ ω. There are non‐isomorphic representable cylindric algebras of dimension α each of which is a generating subreduct of the same β dimensional cylindric algebra. We also show that there exists a representable cylindric algebra ?? of dimension α, such that ?? is a generating subreduct of ?? and ??′, both in CAα +ω , however ?? and ??′ are not isomorphic. This settle questions raised by Henkin, Monk and Tarski (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
In this paper, an extension of first order logic is introduced. In such logics atomic formulas may have infinite lengths. An Omitting Types Theorem is proved. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
Tarek Sayed Ahmed 《Mathematical Logic Quarterly》2008,54(3):294-306
Letn > 2. A weakly representable relation algebra that is not strongly representable is constructed. It is proved that the set of all n by n basic matrices forms a cylindric basis that is also a weakly but not a strongly representable atom structure. This gives an example of a binary generated atomic representable cylindric algebra with no complete representation. An application to first order logic is given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
George Voutsadakis 《Applied Categorical Structures》2002,10(6):531-568
The framework developed by Blok and Pigozzi for the algebraizability of deductive systems is extended to cover the algebraizability of multisignature logics with quantifiers. Institutions are used as the supporting structure in place of deductive systems. In particular, the concept of an algebraic institution and that of an algebraizable institution are made precise using the theory of monads from categorical algebra and the notion of equivalence of institutions introduced by Voutsadakis. Several examples of algebraic and algebraizable institutions are provided. 相似文献
5.
通过两个积分 (一个是不定积分 ,一个是定积分 )及一个极限 ,说明如何灵活使用积分法解决积分问题 ,方法灵活、巧妙 ,适用范围广 . 相似文献
6.
Tarek Sayed Ahmed 《Mathematical Logic Quarterly》2006,52(1):106-112
SC, CA, QA and QEA denote the classes of Pinter's substitution algebras, Tarski's cylindric algebras, Halmos' quasi‐polyadic algebras and quasi‐polyadic equality algebras, respectively. Let ω ≤ α < β and let K ∈ {SC,CA,QA,QEA}. We show that the class of α ‐dimensional neat reducts of algebras in Kβ is not elementary. This solves a problem in [3]. Also our result generalizes results proved in [2] and [3]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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8.
Ramon Jansana 《Mathematical Logic Quarterly》2002,48(3):427-445
The positive fragment of the local modal consequence relation defined by the class of all Kripke frames is studied in the context of Abstract Algebraic Logic. It is shown that this fragment is non‐protoalgebraic and that its class of canonically associated algebras according to the criteria set up in [7] is the class of positive modal algebras. Moreover its full models are characterized as the models of the Gentzen calculus introduced in [3]. 相似文献
9.
In this note we give an interpretation of cylindric algebras as algebras of sentences (rather than formulas) of first order logic. We show that the isomorphism types of such algebras of sentences coincide with the class of neat reducts of cylindric algebras. Also we show how this interpretation sheds light on some recent results. This is done by likening Henkin's Neat Embedding Theorem to his celebrated completeness proof. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
简要叙述了三个擂台赛博弈问题,指出解法[1]的错误所在,其一是将无限延伸的博弈树以有限的形式看待,其二是概率计算过程与结果错误,提出一种新的解法,并比较了结果的大小。 相似文献
11.
We prove that the pure global dimension of a polynomial ring over an integral domain k in a finite or countable number n?2 of commuting (non-commuting, resp.) variables is t + 1, provided . As an application, we determine the pure global dimension of wild algebras of quiver type, also (in case k is an algebraically closed field) of the wild local and wild commutative algebras of finite k-dimension. 相似文献
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13.
A. H. Russell 《The Journal of the Operational Research Society》1976,27(2):351-365
A problem in tree networks, that of minimizing the cost of a pipeline tree connecting a source to a number of sinks, is discussed. A method of solution in which the optimal solution is synthesised from optimized subsystems is described. The method is built on the geometrical properties of the simplest subsystem; that with one source and two sinks. Experience with the method suggests that it is a practical alternative to numerical-iterative methods used hitherto. 相似文献
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16.
A. Hodson A. P. Muhlemann D. H. R. Price 《The Journal of the Operational Research Society》1985,36(10):903-914
This paper presents a scheduling problem with constraints imposed on the waiting time between stages. The process in which it occurs involves the preparation, cooking and chilling of meals. A maximum of 30 min is permitted for waiting between the completion of the cooking stage and the start of chilling down to temperature of <3°C. If this is not achieved, then the food has to be discarded. Clearly the scheduling of the final cooking stage and chilling facilities is crucial in this context. The development of a procedure to do this scheduling, using a microcomputer, is described and some typical results presented. Further uses of the model are briefly outlined. 相似文献
17.
A Solution to Banach's Hyperplane Problem 总被引:4,自引:0,他引:4
An infinite-dimensional Banach space X is constructed whichis not isomorphic to X R. Equivalently, X is not isomorphicto any of its closed subspaces of codimension one. This givesa negative answer to a question of Banach. In fact, X has thestronger property that it is not isomorphic to any proper subspace.It also happens to have an unconditional basis. 相似文献
18.
Tarek Sayed Ahmed 《Mathematical Logic Quarterly》2009,55(3):237-244
We give a simple new construction of representable relation algebras with non‐representable completions. Using variations on our construction, we show that the elementary closure of the class of completely representable relation algebras is not finitely axiomatizable (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
A unified analytic solution to the Busemann-Petty problem was recently found by Gardner, Koldobsky and Schlumprecht. We give an elementary proof of their formulas for the inverse Radon transform of the radial function
of an origin-symmetric star body
. 相似文献
20.
Vesselin Drensky Jie-Tai Yu 《Proceedings of the American Mathematical Society》2008,136(10):3391-3394
We develop a new method to deal with the Cancellation Conjecture of Zariski in different environments. We prove the conjecture for free associative algebras of rank two. We also produce a new proof of the conjecture for polynomial algebras of rank two over fields of zero characteristic.