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  1. Universal Algebra: Fundamentals and Selected Topics, Taylor & Francis, ix+308pp., August 2011.
  2. Algebraic Logic and Universal Algebra in Computer Science, edited with R. Maddux and D. Pigozzi, Lecture Notes in Computer Science, vol. 425, New York, Springer-Verlag, 1990.


  1. Semilattice Sums of Algebras and Mal'tsev Products of Varieties, with T. Penza and A. Romanowska, Algebra Universalis, 81, 33 (2020).
    Here are some additional notes addressing possible generalizations of the main theorem.
  2. Random Models of Idempotent Linear Maltsev Conditions. I. Idemprimality, with A. Szendrei, Algebra Universalis, 81, 9(2020), arxiv
  3. Joins and Maltsev Products of Congruence-Permutable Varieties, Algebra Univers. 81, 16 (2020).   pdf
  4. Universal Algebraic Methods for Constraint Satisfaction Problems, with William DeMeo, Logical Methods in Computer Science, 18 issue 1.
  5. Introducing Boolean semilattices, in "Don Pigozzi on Abstract Algebraic Logic and Universal Algebra," Springer-Verlag, pdf
  6. Automorphism-primal algebras generate verbose varieties, Algebra Universalis, vol. 74 (2015), 117-122.   pdf   DOI 10.1007/s00012-015-0337-0.
  7. Commutative, idempotent groupoids and the constraint satisfaction problem, with David Failing, Algebra Universalis, vol. 73, no. 3-4 (2015), 391-417.   AU version complete manuscript, with appendix   DOI 10.1007/s00012-015-0323-6.
  8. Measuring bias in cyclic random walks, with S. Sethuraman, Missouri J. Math., 25 (2013), 195-212.   pdf
  9. Fully invariant and verbal congruence relations, with J. Berman, Algebra Universalis, 70 (2013), 71-94.   pdf
  10. An automatic, time-based, secure pairing protocol for passive RFID, with G. Amariucai and Y. Guan, Workshop on RFID Security--RFIDSec'11 (Amherst, MA, USA) June 2011.   pdf
  11. An artificial neural network for wavelet steganalysis, with J. Davidson and E. Bartlett, Optics and Photonics, Mathematical Methods in Pattern and Image Analysis, vol 5916, SPIE, 2005, 1-10.   pdf
  12. Unitary embedding for data hiding with the SVD, with J. Davidson, Security, Steganography and Watermarking of Multimedia Contents VII, SPIE, 2005.   pdf
  13. Computational complexity of generators and nongenerators in algebra, with G. Slutzki, Int. J. Algebra and Computation, 12 no. 5, (2002), 719-735.   pdf
  14. Computational complexity of some problems involving congruences on algebras, with G. Slutzki, Theoret. Comp. Sci., 270 (2002), 591-608.   pdf.
    Extended abstract in Fifteenth Annual IEEE Symposium on Logic in Computer Science (LICS 15) IEEE Computer Society, 2000, 168-174.
  15. Complexity of some problems concerning varieties and quasivarieties of algebras, with G. Slutzki, SIAM J. Computing, 30 no. 2 (2000), 359-382.   pdf
    Extended abstract in 16th Symposium on Theoretical Aspects of Computer Science (STACS '99), Lecture Notes in Computer Science, v. 1563, Springer-Verlag, 1999, 163-172.
  16. Computational complexity of term-equivalence, with G. Slutzki, Int. J. Algebra and Computation, 9 no. 1,(1999), 113-128.   pdf
  17. Categorical equivalence of modes, with J. Berman, Discussiones Mathematicae, 19 (1999), 41-62.   pdf
  18. Algorithms for categorical equivalence, with J. Berman, Math. Struc. Comp. Sci., 8 (1998), 1-15.   pdf
  19. Categorical equivalence of algebras with a majority term, Algebra Universalis, 40 (1998), 149-175.   pdf
  20. Morita equivalence of almost-primal clones, with J. Berman, J. Pure Appl. Algebra, 108 (1996), 175-201.   pdf
  21. Subquasivarieties of regularized varieties, with A. Romanowska, Algebra Universalis, 36 (1996), 536-563.   pdf
  22. Structural completeness in algebra and logic, Algebraic Logic (H. Andreka, D. Monk, and I. Nemeti, eds.) pdf
  23. Minimal varieties and quasivarieties, with R. McKenzie, J. Australian Math. Soc., Series A 48 (1990), 133-147. pdf
  24. Non-axiomatizability of the amalgamation class of modular lattice varieties, Order, 6 (1989), 49-58. pdf
  25. Residually small modular varieties with AP, Houston J. Math., 14 (1988), 451-464. pdf
  26. On the relationship of AP, RS, and CEP in congruence modular varieties, II, with R. McKenzie, Proc. AMS, 103 (1988), 335-343.  pdf
  27. Saturated algebras in filtral varieties, Algebra Universalis, 24 (1987), 101-110. pdf
  28. On the relationship of AP, RS, and CEP in modular varieties, Algebra Universalis, 22 (1986), 164-171. pdf
  29. Amalgamation classes of some distributive varieties, Algebra Universalis, 20 (1985), 143-166. pdf
  30. Deductive varieties of modules and related objects, with L. Hogben, Trans. AMS, 289 (1985), 303-320.  pdf
  31. The amalgamation class of a discriminator variety is finitely axiomatizable, Universal Algebra and Lattice Theory (R. Freese and O. Garcia, eds.) Springer-Verlag, New York, 1983. Lecture Notes in Mathematics, vol. 1004, 1-9.   pdf
  32. How to cancel a linearly ordered exponent, with R. McKenzie and Zs. Nagy, Colloquia Mathematica Societatis Janos Bolyai, 29. North-Holland Publishing Co., Amsterdam, 1977, 87-93. pdf