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Algebraic Logic, Where Does it Stand Today?

Published online by Cambridge University Press:  15 January 2014

Tarek Sayed Ahmed*
Affiliation:
Department of Mathematics, Faculty of Science, Cairo University, Giza, Egypt. E-mail: [email protected]

Abstract

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. We relate the algebraic notion of neat embeddings (a notion special to cylindric algebras) to the metalogical ones of provability, interpolation and omitting types in variants of first logic. Another novelty that occurs here is relating the algebraic notion of atom-canonicity for a class of boolean algebras with operators to the metalogical one of omitting types for the corresponding logic. A hitherto unpublished application of algebraic logic to omitting types of first order logic is given. Proofs are included when they serve to illustrate certain concepts. Several open problems are posed. We have tried as much as possible to avoid exploring territory already explored in the survey articles of Monk [93] and Németi [97] in the subject.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2005

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References

REFERENCES

[1] Adamek, J., Herrlich, H., and Strecker, G., Abstract and concrete categories, or the joy of cats, John Wiley and sons, 1990.Google Scholar
[2] Andréka, H., Weakly representable but not representable relation algebras, Algebra Universalis, vol. 28 (1994), pp. 3143.CrossRefGoogle Scholar
[3] Andréka, H., Complexity of equations valid in algebras of relations, Annals of Pure and Applied Logic, vol. 89 (1997), pp. 149209.CrossRefGoogle Scholar
[4] Andréka, H., Atomic representable relation and cylindric algebras with non representable completions, manuscript, 2000.Google Scholar
[5] Andréka, H., Givant, S., Mikulas, S., Németi, I., and Simon, A., Notions of density that imply representability in algebraic logic, Annals of Pure and Applied Logic, vol. 91 (1998), pp. 93190.CrossRefGoogle Scholar
[6] Andréka, H., Givant, S., and Németi, I., Decision problems for equational theories of relation algebras, Memoirs of the American Mathematical Society, vol. 126 (1997), no. 604.CrossRefGoogle Scholar
[7] Andréka, H., Gregely, T., and Németi, I., On universal algebraic constructions of logics, Studia Logica, vol. 36 (1977), pp. 947.CrossRefGoogle Scholar
[8] Andréka, H., Monk, J. D., and Németi, I. (editors), Algebraic Logic, North-Holland, Amsterdam, 1991.Google Scholar
[9] Andréka, H. and Németi, I., A simple purely algebraic proof of the completeness of some first order logics, Algebra Universalis, vol. 5 (1975), pp. 815.CrossRefGoogle Scholar
[10] Andréka, H., Németi, I., and Madarász, J., Relativity theory, Electronically available at http://www.math-inst.hu/pub/algebraic-logic.Google Scholar
[11] Andréka, H., Németi, I., and Ahmed, T. Sayed, Amalgamation in algebras of logic, Logic Journal of the IGPL, to appear. Also, presented in the Universal Algebra Conference held in Szeged, Hungary 1998.Google Scholar
[12] Andréka, H., On neat reducts of algebras of logic (Abstract), this Bulletin, vol. 3 (1997), p. 249.Google Scholar
[13] Andréka, H. and Ahmed, T. Sayed, Omitting types in logics with finitely many variables (Abstract), this Bulletin, vol. 5 (1999), no. 1, p. 88.Google Scholar
[14] Andréka, H. and Thompson, R. J., A stone-type representation theorem for algebras of relations of higher rank, Transactions of the American Mathematical Society, vol. 309 (1988), no. 2, pp. 671682.Google Scholar
[15] Andréka, H., Van Benthem, J., and Németi, I., Modal languages and bounded fragments of predicate logic, Journal of Philosophical Logic, vol. 27 (1998), pp. 217274.CrossRefGoogle Scholar
[16] Anellis, H. and Houser, N., Nineteenth century roots of algebraic logic and universal algebra, In Andréka et al. [8], pp. 137.Google Scholar
[17] Biró, B., Non-finite axiomatizability results in algebraic logic, The Journal of Symbolic Logic, vol. 57 (1992), no. 3, pp. 832843.CrossRefGoogle Scholar
[18] Biro, B. and Shelah, S., Isomorphic but not lower base isomorphic cylindric set algebras, The Journal of Symbolic Logic, vol. 53 (1988), no. 3, pp. 846853.CrossRefGoogle Scholar
[19] Blok, W. J. and Pigozzi, D., Algebraizable logics, Memoirs of American Mathematical Society, vol. 77 (1989), no. 398.CrossRefGoogle Scholar
[20] Casanovas, E. and Farre, R., Omitting types in incomplete theories, The Journal of Symbolic Logic, vol. 61 (1996), no. 1, pp. 236245.CrossRefGoogle Scholar
[21] Chang, C. and Keisler, H. J., Model Theory, North Holland, 1994.Google Scholar
[22] Comer, S. D., A Sheaf theoretic duality theory for cylindric algebras, Transactions of the American Mathematical Society, vol. 169 (1985), pp. 7587.CrossRefGoogle Scholar
[23] Comer, S. D., The representation of 3 dimensional cylindric algebras, In Andréka et al. [8], pp. 146172.Google Scholar
[24] Craig, W., Logic in Algebraic Form, North Holland, Amsterdam, 1974.Google Scholar
[25] Daigneault, A. and Monk, J. D., Representation theory for polyadic algebras, Fundamenta Mathematicae, vol. 52 (1963), pp. 151176.CrossRefGoogle Scholar
[26] De Morgan, A., On the syllogism, no. IV, and on the logic of relations, Transactions of the Cambridge Philosophical Society, vol. 10 (1864), pp. 331358, Republished in [27].Google Scholar
[27] De Morgan, A., On the syllogism and other logical writings, Rare masterpieces of philosophy and science (Heath, P., editor), Routledge & Kegan Paul, 1966.Google Scholar
[28] Etesi, G. and Németi, I., On the effective computability of non-recursive functions via Malament-Hogarth space-times, International Journal of Theoretical Physics, (2002), Electronically available at: http//www.bu.edu/wcp/Papers/Scie/ScieDarv.htm.CrossRefGoogle Scholar
[29] Ferenczi, M., On representability of cylindric algebras, Abstracts of papers presented to the American Mathematical Society, vol. 13 (1992), no. 3, p. 336.Google Scholar
[30] Gabbay, D. M., An irreflexitivity lemma with applications to axiomatizations of conditions in linear frames, Aspects of Philosophical Logic (Mönnich, U., editor), Reidel, Dordrecht, 1981.Google Scholar
[31] Givant, S. and Andréka, H., Groups and algebras of binary relations, this Bulletin, vol. 8 (2002), pp. 3864.Google Scholar
[32] Goldblatt, R., On the role of the Baire category theorem and dependent choice in the foundations of logic, The Journal of Symbolic Logic, vol. 50 (1985), no. 2, pp. 412422.CrossRefGoogle Scholar
[33] Goldblatt, R., Varieties of complex algebras, Annals of Pure and Applied Logic, vol. 38 (1989), pp. 173241.CrossRefGoogle Scholar
[34] Goldblatt, R., On closure under canonical embedding algebras, In Andréka et al. [8], pp. 217231.Google Scholar
[35] Goldblatt, R., Algebraic polymodal logic: A survey, Logic Journal of the IGPL, vol. 8 (2000), no. 4, pp. 393450.CrossRefGoogle Scholar
[36] Goldblatt, R., Persistence and atomic generation for atomic boolean algebras with operators, Studia Logica, vol. 68 (2001), no. 2, pp. 155171.CrossRefGoogle Scholar
[37] Halmos, P., Algebraic Logic, Chelsea Publishing Co., New York, 1962.Google Scholar
[38] Halmos, P., An autobiography of polyadic algebras, Logic Journal of the IGPL, vol. 8 (1998), no. 4, pp. 363392.Google Scholar
[39] Henkin, L. and Monk, J. D., Cylindric algebras and related structures, Proceedings of the Tarski Symposium, vol. 25, American Mathematical Society, 1974, pp. 105–21.CrossRefGoogle Scholar
[40] Henkin, L., Monk, J. D., and Tarski, A., Cylindric Algebras: Part I, North Holland, 1971.Google Scholar
[41] Henkin, L., Cylindric Algebras: Part II, North Holland, 1985.Google Scholar
[42] Hirsch, R., Personal communication.Google Scholar
[43] Hirsch, R. and Hodkinson, I., Complete representations in algebraic logic, The Journal of Symbolic Logic, vol. 62 (1997), no. 3, pp. 816847.CrossRefGoogle Scholar
[44] Hirsch, R., Step by step-building representations in algebraic logic, The Journal of Symbolic Logic, vol. 62 (1997), no. 1, pp. 225279.CrossRefGoogle Scholar
[45] Hirsch, R., Synthesizing axioms by games, JFAK. Essays dedicated to Johan van Benthem on the occassion of his 50th birthday. CD-ROM. (Gerbrandy, Jelle, Marx, Maarten, de Rijke, Maarten, and Venema, Yde, editors), Amsterdam University Press, 1999.Google Scholar
[46] Hirsch, R., Relational algebras with n-dimensional relational bases, Annals of Pure and Applied Logic, vol. 101 (2000), pp. 227274.CrossRefGoogle Scholar
[47] Hirsch, R., Relation algebras from cylindric algebras, I, Annals of Pure and Applied Logic, vol. 112 (2001), pp. 225266.CrossRefGoogle Scholar
[48] Hirsch, R., Relation algebras from cylindric algebras, II, Annals of Pure and Applied Logic, vol. 112 (2001), pp. 267297.CrossRefGoogle Scholar
[49] Hirsch, R., Representability is not decidable for finite relation algebras, Transactions of the American Mathematical Society, vol. 353 (2001), pp. 14031425.CrossRefGoogle Scholar
[50] Hirsch, R., Relation algebras by games, Studies in Logic and the Foundations of Mathematics, vol. 147, 2002.Google Scholar
[51] Hirsch, R., Strongly representable atom structures, Proceedings of the American Mathematical Society, vol. 130 (2002), pp. 18191831.CrossRefGoogle Scholar
[52] Hirsch, R., Hodkinson, I., and Kurucz, A., On modal logics between K × K × K and S5 × S5 × S5, The Journal of Symbolic Logic, vol. 67 (2002), no. 1, pp. 221234.CrossRefGoogle Scholar
[53] Hirsch, R., Hodkinson, I., and Maddux, R., On provability with finitely many variables, this Bulletin, vol. 8 (2002), no. 3, pp. 329347.Google Scholar
[54] Hirsch, R., Relation algebra reducts of cylindric algebras and an application to proof theory, The Journal of Symbolic Logic, vol. 67 (2002), no. 1, pp. 197213.CrossRefGoogle Scholar
[55] Hirsch, R. and Ahmed, T. Sayed, The class of relation algebras with n-dimensional hyperbasis and the class RaCAn are not elementary, manuscript, 2001.Google Scholar
[56] Hirsch, R., Neat embeddability is not sufficient for complete representations, manuscript, 2001.Google Scholar
[57] Hodges, W., Model Theory, Encyclopedia of Mathematics and its Applications, vol. 42, Cambridge University Press, 1993.CrossRefGoogle Scholar
[58] Hodges, W., A Shorter Model Theory, Cambridge University Press, 1995.Google Scholar
[59] Hodkinson, I., Atom structures of cylindric algebras and relation algebras, Annals of Pure and Applied Logic, vol. 89 (1997), pp. 117148.CrossRefGoogle Scholar
[60] Hodkinson, I. and Mikulás, Sz., Non-finite axiomatizability of algebras of relations, Algebra Universalis, vol. 43 (2000), pp. 127156.CrossRefGoogle Scholar
[61] Jónsson, B., The theory of binary relations, In Andréka et al. [8], pp. 245292.Google Scholar
[62] Jónsson, B. and Tarski, A., Representation problems for relation algebras, Bulletin of American Mathematical Society, vol. 54 (1948), pp. 8092.Google Scholar
[63] Lyndon, R., The representation of relational algebras, Annals of Mathematics, vol. 51 (1950), no. 3, pp. 707729.CrossRefGoogle Scholar
[64] Lyndon, R., The representation of relational algebras, II, Annals of Mathematics, vol. 63 (1956), no. 2, pp. 294307.CrossRefGoogle Scholar
[65] Lyndon, R., Relation algebras and projective geometries, Michigan Mathematics Journal, vol. 8 (1961), pp. 207220.CrossRefGoogle Scholar
[66] Madarász, J., Logic and relativity (in the light of definability theory), Ph.D. thesis, Alfred Renyi Institute of Mathematics, Hungarian Academy of Sciences, Budapest, 02 26, 2002.Google Scholar
[67] Madarász, J., Hereditary non-finite axiomatizability of relation algebras and their variants, Manuscript consists of 3 TeX pages and 18 handwritten pages.Google Scholar
[68] Madarász, J. and Ahmed, T. Sayed, Amalgamation, interpolation and epimorphisms, solutions to all problems of Pigozzi's paper, and some more, Preprint of the Mathematical Institute of the Hungarian Academy of Sciences.Google Scholar
[69] Maddux, R., The equational theory of CA3 is undecidable, The Journal of Symbolic Logic, vol. 45 (1980), no. 2, pp. 311316.CrossRefGoogle Scholar
[70] Maddux, R., A sequent calculus for relation algebras, Annals of Pure and Applied Logic, vol. 25 (1983), pp. 73101.CrossRefGoogle Scholar
[71] Maddux, R., Canonical relativized cylindric set algebras, Proceedings of the American Mathematical Society, vol. 107 (1989), no. 2, pp. 46504678.CrossRefGoogle Scholar
[72] Maddux, R., Finitary algebraic logic, Zeitschrift für Mathematische Logik und Grundlagen der Mathematik, vol. 35 (1989), pp. 321332.CrossRefGoogle Scholar
[73] Maddux, R., Non-finite axiomatizability results for cylindric and relational algebras, The Journal of Symbolic Logic, vol. 54 (1989), no. 3, pp. 951974.CrossRefGoogle Scholar
[74] Maddux, R., The neat embedding property and the number of variables required in proofs, Proceedings of the Americal Mathematical Society, vol. 112 (1991), pp. 195202.CrossRefGoogle Scholar
[75] Maddux, R., Relation algebras of every dimension, The Journal of Symbolic Logic, vol. 57 (1992), no. 4, pp. 12131229.CrossRefGoogle Scholar
[76] Maddux, R., Finitary algebraic logic, II, Mathematical Logic Quarterly, vol. 39 (1993), pp. 566569.CrossRefGoogle Scholar
[77] Maddux, R., Finitary axiomatizations of the true relational equations, Algebraic Methods in Logic and in Computer Science (Rauszer, C., editor), vol. 28, Banach Center Publications, Institute of Mathematics, Polish Academy of Sciences, 1993, pp. 201208.Google Scholar
[78] Maddux, R., Undecidable semi-associative relation algebras, The Journal of Symbolic Logic, vol. 59 (1994), pp. 398418.CrossRefGoogle Scholar
[79] Makkai, M., On PCΔ classes in the theory of models, Matemtikai Kutato Intezetenek Kozlemenyei, vol. 9 (1964), pp. 159194.Google Scholar
[80] Maksimova, L., Amalgamation and interpolation in normalmodal logics, Studia Logica, vol. 50 (1991), pp. 457471.CrossRefGoogle Scholar
[81] Marx, M., Algebraic relativization and arrow logic, Ph.D. thesis, University of Amsterdam, 1995.Google Scholar
[82] Marx, M., Relativized relation algebras, Algebra Universalis, vol. 41 (1999), pp. 2345.CrossRefGoogle Scholar
[83] Marx, M., Polos, L., and Masuch, M. (editors), Arrow logic and multi-modal logic, Studies in Logic, Language and Information, CSLI Publications, Centre for the Study of Language and Information, 1996.Google Scholar
[84] McKenzie, R., The representation of relation algebras, Ph.D. thesis, University of Colorado at Boulder, 1966.Google Scholar
[85] Monk, J. D., On representable relation algebras, Michigan Mathematics, vol. 11 (1964), pp. 207210.Google Scholar
[86] Monk, J. D., Model-theoretic methods and results in the theory of cylindric algebras, The theory of models (Addison, J. W., Henkin, L., and Tarski, A., editors), North-Holland, Amsterdam, 1965, pp. 238250.Google Scholar
[87] Monk, J. D., Non-finitizability of classes of representable cylindric algebras, The Journal of Symbolic Logic, vol. 34 (1969), pp. 331343.CrossRefGoogle Scholar
[88] Monk, J. D., On an algebra of sets of finite sequences, The Journal of Symbolic Logic, vol. 35 (1970), pp. 1928.CrossRefGoogle Scholar
[89] Monk, J. D., Provability with finitely many variables, Proceedings of the American Mathematical Society, vol. 27 (1971), pp. 353358.CrossRefGoogle Scholar
[90] Monk, J. D., Connections between combinatorial theory and algebraic logic, Studies in Mathematics, vol. 9, Mathematical Association of America, 1974, pp. 5891.Google Scholar
[91] Monk, J. D., Open problems, In Andréka et al. [8], pp. 727746.Google Scholar
[92] Monk, J. D., Remarks on the problems in the books Cylindric Algebras, Part I and Part II and Cylindric Set Algebras, In Andréka et al. [8], pp. 723726.Google Scholar
[93] Monk, J. D., An introduction to cylindric set algebras, Logic Journal of the IGPL, vol. 8 (2000), no. 4, pp. 346392.CrossRefGoogle Scholar
[94] Németi, I., The class of neat reducts of cylindric algebras is not a variety but is closed w.r.t. HP, Notre Dame Journal of Formal logic, vol. 24 (1983), no. 3, pp. 399409.CrossRefGoogle Scholar
[95] Németi, I., Cylindric relativized set algebras have the strong amalgamation property, The Journal of Symbolic Logic, vol. 50 (1985), no. 3, pp. 689700.CrossRefGoogle Scholar
[96] Németi, I., Free algebras and decidability in algebraic logic, Ph.D. thesis, Hungarian Academy of Sciences, 1986.Google Scholar
[97] Németi, I., Algebraization of quantifier logics, an introductory overview, Preprint of the Mathematical Institute of the Hungarian Academy of Sciences (No 13-1996), 1996. A shortened version appeared in Studia Logica, vol. 50 (1991), pp. 465569.Google Scholar
[98] Németi, I., Strong representability of fork algebras, a set theoretic foundation, Logic Journal of the IGPL, vol. 5 (1997), no. 1, pp. 828.CrossRefGoogle Scholar
[99] Németi, I. and Sági, G., On the equational theory of representable polyadic algebras, The Journal of Symbolic Logic, vol. 65 (2000), pp. 11431167.CrossRefGoogle Scholar
[100] Newelski, L., Omitting types and the real line, The Journal of Symbolic Logic, vol. 52 (1987), pp. 10201026.CrossRefGoogle Scholar
[101] Pigozzi, D., Amalgamation, congruence extension, and interpolation properties in algebras, Algebra Universalis, vol. 1 (1971), pp. 269349.CrossRefGoogle Scholar
[102] Sági, G., On the finitization problem of algebraic logic, Ph.D. thesis, Technical University of Budapest, 1999.Google Scholar
[103] Sági, G., A completeness theorem for higher order logics, The Journal of Symbolic Logic, vol. 65 (2000), no. 3, pp. 857884.CrossRefGoogle Scholar
[104] Sági, G. and Ahmed, T. Sayed, Németi's directed cylindric algebras have the strong amalgamation property, manuscript, 1999.Google Scholar
[105] Sági, G., Ahmed, T. Sayed, and Sain, I., The finitization problem in algebraic logic, a survey, manuscript, 2000.Google Scholar
[106] Sain, I., Searching for a finitizable algebraization of first order logic, Logic Jornal of the IGPL, vol. 8 (2000), no. 4, pp. 495589.Google Scholar
[107] Sain, I. and Gyuris, V., Finite schematizable algebraic logic, Logic Jornal of the IGPL, vol. 8 (1997), pp. 699751.CrossRefGoogle Scholar
[108] Sain, I. and Németi, I., Fork algebras in usual and in non-well founded set theories (An overview), Preprint of the Mathematical Institute of the Hungarian Academy of Sciences.Google Scholar
[109] Ahmed, T. Sayed, The class of neat reducts is not elementary (Abstract), this Bulletin, vol. 5 (1999), no. 3, pp. 407408.Google Scholar
[110] Ahmed, T. Sayed, The class of neat reducts is not elementary, Logic Journal of the IGPL, vol. 9 (2001), pp. 3165.Google Scholar
[111] Ahmed, T. Sayed, On neat reducts and amalgamation (Abstract), this Bulletin, vol. 7 (2001), no. 1.Google Scholar
[112] Ahmed, T. Sayed, Reducts of L3 has Gödel's incompleteness, therefore the free quasipolyadic algebras of dimension 3 are not atomic, manuscript, 2001.Google Scholar
[113] Ahmed, T. Sayed, The class of 2-dimensional neat reducts of polyadic algebras is not elementary, Fundementa Mathematicae, vol. 172 (2002), pp. 6181.CrossRefGoogle Scholar
[114] Ahmed, T. Sayed, Martin's axiom, omitting types and complete representations in algebraic logic, Studia Logica, vol. 72 (2002), pp. 125.CrossRefGoogle Scholar
[115] Ahmed, T. Sayed, A model-theoretic solution to a problem of Tarski, Mathematical Logic Quarterly, vol. 48 (2002), no. 3, pp. 343355.3.0.CO;2-4>CrossRefGoogle Scholar
[116] Ahmed, T. Sayed, On neat reducts of algebras of logic, Ph.D. thesis, Cairo University, 2002.Google Scholar
[117] Ahmed, T. Sayed, Omitting types for finite variable fragments of first order logic, Bulletin of the Section of Logic, vol. 32 (2003), no. 3, pp. 103107.Google Scholar
[118] Ahmed, T. Sayed, On amalgamation of reducts of polyadic algebras, Algebra Universalis, vol. 51 (2004), pp. 301359.CrossRefGoogle Scholar
[119] Ahmed, T. Sayed, On a stronger version of the finitization problem, Proceedings of the Conference in Algebra (in honor of the 70th birthday of Ervin Fried) (Alfred Rényi Institute of Mathematics, Budapest, Hungary), Electronically available at http://www.renyi.hu/~rabbit/.Google Scholar
[120] Ahmed, T. Sayed, A categorical approach to amalgamation theorems, Archive of Mathematical Logic, to appear.Google Scholar
[121] Ahmed, T. Sayed, Omitting types for algebraizable extensions of first order logic, Logic Journal of the IGPL, to appear.Google Scholar
[122] Ahmed, T. Sayed, On amalgamation of algebras of logics, a functorial formulation, in preparation.Google Scholar
[123] Ahmed, T. Sayed, On the closure of the class of neat reducts under various operators, submitted.Google Scholar
[124] Ahmed, T. Sayed, On the completeness and incompleteness of finite variable fragments of first order logic, submitted.Google Scholar
[125] Ahmed, T. Sayed, On the finitization problem for cylindric algebras, submitted.Google Scholar
[126] Ahmed, T. Sayed, RCAω is not Sahlqvist, and is not closed under minimal completions, submitted.Google Scholar
[127] Ahmed, T. Sayed, The class of strongly representable atomstructures of RCA3 is not elementary. In particular, RCA3 is not single-persistent, submitted.Google Scholar
[128] Ahmed, T. Sayed, Which reducts of polyadic algebras are atom-canonical?, submitted.Google Scholar
[129] Ahmed, T. Sayed and Németi, I., On neat reducts of algebras of logic, Studia Logica, vol. 68 (2001), pp. 229262.CrossRefGoogle Scholar
[130] Shelah, S., On a problem in cylindric algebra, In Andréka et al. [8], pp. 645664.Google Scholar
[131] Simon, A., What the finitization problem is not, Algebraic Methods in Logic and in Computer Science, Banach Centre Publications, 1993, pp. 95116.Google Scholar
[132] Simon, A., Non representable algebras of relations, Ph.D. thesis, Alfred Renyi Institute of Mathematics, Hungarian Academy of Sciences, 1997.Google Scholar
[133] Tarski, A. and Givant, S., A formalization of set theory without variables, vol. 41, American Mathematical Society Colloquium Publications, 1987.Google Scholar
[134] Tarski, A., Tarski's system of geometry, this Bulletin, vol. 5 (1999), pp. 175214.Google Scholar
[135] Venema, Y., Cylindric modal logic, The Journal of Symbolic Logic, vol. 60 (1995), no. 2, pp. 591623.CrossRefGoogle Scholar
[136] Venema, Y., Atom structures and Sahlqvist equations, Algebra Universalis, vol. 38 (1998), pp. 185199.CrossRefGoogle Scholar
[137] Venema, Y., Rectangular games, The Journal of Symbolic Logic, vol. 63 (1998), no. 4, pp. 15491564.CrossRefGoogle Scholar
[138] Weaver, G. and Welaish, J., Back and forth construction in modal logic an interpolation theorem for a family of modal logics, The Journal of Symbolic Logic, vol. 51 (1986), no. 4, pp. 969980.CrossRefGoogle Scholar