ISSN:
1572-9273
Keywords:
05A15
;
06B05
;
Incidence structure
;
graph
;
glued lattice
;
glued tolerance relation
;
skeleton
;
Dilworth's theorem
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mathematics
Notes:
Abstract A tolerance relation θ of a lattice L, i.e., a reflexive and symmetric relation of L which is compatible with join and meet, is called glued if covering blocks of θ have nonempty intersection. For a lattice L with a glued tolerance relation we prove a formula counting the number of elements of L with exactly k lower (upper) covers. Moreover, we prove similar formulas for incidence structures and graphs and we give a new proof of Dilworth's covering theorem.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00383603
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