Abstract
The concept of `adjunct' operation of two lattices with respect to a pair of elements is introduced. A structure theorem namely, `A finite lattice is dismantlable if and only if it is an adjunct of chains' is obtained. Further it is established that for any adjunct representation of a dismantlable lattice the number of chains as well as the number of times a pair of elements occurs remains the same. If a dismantlable lattice L has n elements and n+k edges then it is proved that the number of irreducible elements of L lies between n-2k-2 and n-2. These results are used to enumerate the class of lattices with exactly two reducible elements, the class of lattices with n elements and upto n+1 edges, and their subclasses of distributive lattices and modular lattices.
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Thakare, N.K., Pawar, M.M. & Waphare, B.N. A structure theorem for dismantlable lattices and enumeration. Periodica Mathematica Hungarica 45, 147–160 (2002). https://doi.org/10.1023/A:1022314517291
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DOI: https://doi.org/10.1023/A:1022314517291