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  1. Tarek Sayed Ahmed (2011). On the Complexity of Axiomatizations of the Class of Representable Quasi‐Polyadic Equality Algebras. Mathematical Logic Quarterly 57 (4):384-394.
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  2. Tarek Sayed Ahmed (2010). The Class of Polyadic Algebras has the Super Amalgamation Property. Mathematical Logic Quarterly 56 (1):103-112.
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  3. Tarek Sayed Ahmed (2009). A Note on Substitutions in Representable Cylindric Algebras. Mathematical Logic Quarterly 55 (3):280-287.
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  4. Tarek Sayed Ahmed (2009). A Simple Construction of Representable Relation Algebras with Non‐Representable Completions. Mathematical Logic Quarterly 55 (3):237-244.
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  5. Tarek Sayed Ahmed (2009). On a Theorem of Vaught for First Order Logic with Finitely Many Variables. Journal of Applied Non-Classical Logics 19 (1):97-112.
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  6. Tarek Sayed Ahmed (2009). On Neat Embeddings of Cylindric Algebras. Mathematical Logic Quarterly 55 (6):666-668.
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  7. Mohamed Khaled & Tarek Sayed Ahmed (2009). Classes of Algebras That Are Not Closed Under Completions. Bulletin of the Section of Logic 38 (1/2):29-43.
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  8. Tarek Sayed Ahmed (2008). Amalgamation for Reducts of Polyadic Equality Algebras, a Negative Result. Bulletin of the Section of Logic 37 (1):37-50.
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  9. Tarek Sayed Ahmed (2008). Classes of Representable Algebras with the Amalgamation Property. Bulletin of the Section of Logic 37 (2):115-121.
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  10. Tarek Sayed Ahmed (2008). On Complete Representations of Reducts of Polyadic Algebras. Studia Logica 89 (3):325 - 332.
    Following research initiated by Tarski, Craig and Németi, and futher pursued by Sain and others, we show that for certain subsets G of ω ω, atomic countable G polyadic algebras are completely representable. G polyadic algebras are obtained by restricting the similarity type and axiomatization of ω-dimensional polyadic algebras to finite quantifiers and substitutions in G. This contrasts the cases of cylindric and relation algebras.
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  11. Tarek Sayed Ahmed (2008). Racan is Not Elementary, for N≥ 5. Bulletin of the Section of Logic 37 (2):123-136.
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  12. Tarek Sayed Ahmed (2008). The Class of Neat Reducts is Not Boolean Closed. Bulletin of the Section of Logic 37 (1):51-61.
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  13. Tarek Sayed Ahmed (2008). Weakly Representable Atom Structures That Are Not Strongly Representable, with an Application to First Order Logic. Mathematical Logic Quarterly 54 (3):294-306.
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  14. Hajnal Andréka, István Németi & Tarek Sayed Ahmed (2008). Omitting Types for Finite Variable Fragments and Complete Representations of Algebras. Journal of Symbolic Logic 73 (1):65-89.
    We give a novel application of algebraic logic to first order logic. A new, flexible construction is presented for representable but not completely representable atomic relation and cylindric algebras of dimension n (for finite n > 2) with the additional property that they are one-generated and the set of all n by n atomic matrices forms a cylindric basis. We use this construction to show that the classical Henkin-Orey omitting types theorem fails for the finite variable fragments of first order (...)
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  15. Tarek Sayed Ahmed (2007). A Note on Neat Reducts. Studia Logica 85 (2):139 - 151.
    SC, CA, QA and QEA denote the class of Pinter’s substitution algebras, Tarski’s cylindric algebras, Halmos’ quasi-polyadic and quasi-polyadic equality algebras, respectively. Let . and . We show that the class of n dimensional neat reducts of algebras in K m is not elementary. This solves a problem in [2]. Also our result generalizes results proved in [1] and [2].
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  16. Tarek Sayed Ahmed (2007). A Non-Finitizability Result in Algebraic Logic. Bulletin of the Section of Logic 36 (1/2):21-27.
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  17. Tarek Sayed Ahmed & Basim Samir (2007). An Omitting Types Theorem for First Order Logic with Infinitary Relation Symbols. Mathematical Logic Quarterly 53 (6):564-570.
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  18. Tarek Sayed Ahmed (2006). Algebras of Sentences. Bulletin of the Section of Logic 35 (1):1-10.
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  19. Tarek Sayed Ahmed & Basim Samir (2006). Neat Embeddings and Amalgamation. Bulletin of the Section of Logic 35 (4):163-171.
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  20. Tarek Sayed Ahmed (2005). An Independence Result in Algebraic Logic. Bulletin of the Section of Logic 34 (1):29-36.
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  21. Tarek Sayed Ahmed (2005). Algebraic Logic, Where Does It Stand Today? Bulletin of Symbolic Logic 11 (4):465-516.
    This is a survey article on algebraic logic. It gives a historical background leading up to a modern perspective. Central problems in algebraic logic (like the representation problem) are discussed in connection to other branches of logic, like modal logic, proof theory, model-theoretic forcing, finite combinatorics, and Gödel's incompleteness results. We focus on cylindric algebras. Relation algebras and polyadic algebras are mostly covered only insofar as they relate to cylindric algebras, and even there we have not told the whole story. (...)
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  22. Tarek Sayed Ahmed (2005). A Sufficient and Necessary Condition for Omitting Types. Bulletin of the Section of Logic 34 (1):23-27.
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  23. Tarek Sayed Ahmed (2005). On Amalgamation in Algebras of Logic. Studia Logica 81 (1):61 - 77.
    We show that not all epimorphisms are surjective in certain classes of infinite dimensional cylindric algebras, Pinter's substitution algebras and Halmos' quasipolyadic algebras with and without equality. It follows that these classes fail to have the strong amalgamation property. This answers a question in [3] and a question of Pigozzi in his landmark paper on amalgamation [9]. The cylindric case was first proved by Judit Madarasz [7]. The proof presented herein is substantially different. By a result of Németi, our result (...)
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  24. Tarek Sayed Ahmed (2005). Omitting Types for Algebraizable Extensions of First Order Logic. Journal of Applied Non-Classical Logics 15 (4):465-489.
    We prove an Omitting Types Theorem for certain algebraizable extensions of first order logic without equality studied in [SAI 00] and [SAY 04]. This is done by proving a representation theorem preserving given countable sets of infinite meets for certain reducts of ?- dimensional polyadic algebras, the so-called G polyadic algebras (Theorem 5). Here G is a special subsemigroup of (?, ? o) that specifies the signature of the algebras in question. We state and prove an independence result connecting our (...)
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  25. Tarek Sayed Ahmed (2003). Neat Embeddings, Omitting Types, and Interpolation: An Overview. Notre Dame Journal of Formal Logic 44 (3):157-173.
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  26. Tarek Sayed Ahmed (2002). A Modeltheoretic Solution to a Problem of Tarski. Mathematical Logic Quarterly 48 (3):343-355.
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  27. Tarek Sayed Ahmed (2002). Martin's Axiom, Omitting Types, and Complete Representations in Algebraic Logic. Studia Logica 72 (2):285 - 309.
    We give a new characterization of the class of completely representable cylindric algebras of dimension 2 #lt; n w via special neat embeddings. We prove an independence result connecting cylindric algebra to Martin''s axiom. Finally we apply our results to finite-variable first order logic showing that Henkin and Orey''s omitting types theorem fails for L n, the first order logic restricted to the first n variables when 2 #lt; n#lt;w. L n has been recently (and quite extensively) studied as a (...)
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  28. Tarek Sayed Ahmed & Istvan Németi (2001). On Neat Reducts of Algebras of Logic. Studia Logica 68 (2):229-262.
    SC , CA , QA and QEA stand for the classes of Pinter's substitution algebras, Tarski's cylindric algebras, Halmos' quasipolyadic algebras, and quasipolyadic equality algebras of dimension , respectively. Generalizing a result of Németi on cylindric algebras, we show that for K {SC, CA, QA, QEA} and ordinals , the class Nr K of -dimensional neat reducts of -dimensional K algebras, though closed under taking homomorphic images and products, is not closed under forming subalgebras (i.e. is not a variety) if (...)
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