N. Ackerman, Completeness in generalized ultrametric spaces. p-Adic Numbers Ultrametric Anal, Appl, vol.5, issue.2, pp.89-105, 2013.
DOI : 10.1134/s2070046613020015

E. F. Codd, A relational model of data for large shared data banks, Communications of the ACM, vol.13, issue.6, pp.377-387, 1970.
DOI : 10.1145/362384.362685

B. A. Davey and H. A. Priestley, Introduction to Lattices and Order, 2002.
DOI : 10.1017/CBO9780511809088

R. Dyckhoff and W. Tholen, Exponentiable morphisms, partial products and pullback complements, Journal of Pure and Applied Algebra, vol.49, issue.1-2, pp.103-116, 1987.
DOI : 10.1016/0022-4049(87)90124-1
URL : https://doi.org/10.1016/0022-4049(87)90124-1

R. Freese, J. Je?ek, and J. Nation, Free lattices, 1995.
DOI : 10.1090/surv/042

D. M. Gabbay, Selective filtration in modal logic Part A. Semantic tableaux method, Theoria, vol.34, issue.3, pp.323-330, 1970.
DOI : 10.1111/j.1755-2567.1970.tb00430.x

G. , G. Wehrung, and R. Wille, General Lattice Theory New appendices by the author with, 1998.

R. Hammack, W. Imrich, and S. Klavzar, Handbook of Product Graphs, 2011.

R. Hirsch and I. Hodkinson, Representability is not decidable for finite relation algebras, Transactions of the American Mathematical Society, vol.353, issue.04, pp.1403-1425, 2001.
DOI : 10.1090/S0002-9947-99-02264-3

R. Hirsch, I. Hodkinson, and A. Kurucz, Abstract, The Journal of Symbolic Logic, vol.34, issue.01, pp.221-234, 2002.
DOI : 10.1093/logcom/9.2.197

W. Imrich and S. Klavar, Product graphs. Wiley-Interscience Series in Discrete Mathematics and Optimization, Structure and recognition, 2000.

B. Jacobs, Categorical logic and type theory, volume 141 of Studies in Logic and the Foundations of Mathematics, 1999.

E. M. Jawhari, M. Pouzet, and I. , A classification of reflexive graphs: the use of ``holes'', Journal canadien de math??matiques, vol.38, issue.6, pp.1299-1328, 1986.
DOI : 10.4153/CJM-1986-066-9

A. Kurucz, 15 Combining modal logics, Handbook of Modal Logic of Studies in Logic and Practical Reasoning, pp.869-924, 2007.
DOI : 10.1016/S1570-2464(07)80018-8

F. W. Lawvere, Metric spaces, generalized logic, and closed categories, Rendiconti del Seminario Matematico e Fisico di Milano, vol.43, issue.1, pp.135-166, 1973.
DOI : 10.1007/BF02924844

T. Litak, S. Mikuls, and J. Hidders, Relational lattices: From databases to universal algebra, Journal of Logical and Algebraic Methods in Programming, vol.85, issue.4, pp.540-573, 2016.
DOI : 10.1016/j.jlamp.2015.11.008

R. Maddux, The equational theory of CA 3 is undecidable, The Journal of Symbolic Logic, vol.43, issue.02, pp.311-316, 1980.
DOI : 10.1002/malq.19750210118

S. Priess-crampe and P. Ribemboim, Equivalence relations and spherically complete ultrametric spaces, 20] L. Santocanale. A duality for finite lattices. Preprint, pp.1187-1192, 1995.

L. Santocanale, Relational Lattices via Duality, Coalgebraic Methods in Computer Science CMCS Lecture Notes in Computer Science, vol.320, issue.1, pp.195-215, 2016.
DOI : 10.1007/BF01188998
URL : https://hal.archives-ouvertes.fr/hal-01446027

L. Santocanale, Embeddability into Relational Lattices Is Undecidable, Relational and Algebraic Methods in Computer Science -16th International Conference Proceedings, pp.258-273, 2017.
DOI : 10.1007/978-3-319-40370-0_12
URL : https://hal.archives-ouvertes.fr/hal-01474822

L. Santocanale and F. Wehrung, The equational theory of the weak order on finite symmetric groups. 41 pages, 2014.
URL : https://hal.archives-ouvertes.fr/hal-00986148

M. Spight and V. Tropashko, Relational lattice axioms. Preprint available from http, 2008.

V. Tropashko, Relational algebra as non-distributive lattice. Preprint, available from http, 2006.

L. Santocanale, L. , and C. Umr, Aix-Marseille Université E-mail address: luigi