Families of Subsets Without a Given Poset in Double Chains and Boolean Lattices

Order ◽  
2017 ◽  
Vol 35 (2) ◽  
pp. 349-362
Author(s):  
Jun-Yi Guo ◽  
Fei-Huang Chang ◽  
Hong-Bin Chen ◽  
Wei-Tian Li
2018 ◽  
Vol 25 (02) ◽  
pp. 285-294 ◽  
Author(s):  
Alejandro Alvarado-García ◽  
César Cejudo-Castilla ◽  
Hugo Alberto Rincón-Mejía ◽  
Ivan Fernando Vilchis-Montalvo ◽  
Manuel Gerardo Zorrilla-Noriega

Some properties of and relations between several (big) lattices of module classes are used in this paper to obtain information about the ring over which modules are taken. The authors reach characterizations of trivial rings, semisimple rings and certain rings over which every torsion theory is hereditary.


1981 ◽  
Vol 31 (4) ◽  
pp. 481-485 ◽  
Author(s):  
D. E. Daykin ◽  
P. Frankl ◽  
C. Greene ◽  
A. J. W. Hilton

AbstractSome generalizations of Sperner's theorem and of the LYM inequality are given to the case when A1,… At are t families of subsets of {1,…,m} such that a set in one family does not properly contain a set in another.


2015 ◽  
Vol 16 (1) ◽  
pp. 111-138 ◽  
Author(s):  
NICOLAS SCHWIND ◽  
KATSUMI INOUE

AbstractWe address the problem of belief revision of logic programs (LPs), i.e., how to incorporate to a LP P a new LP Q. Based on the structure of SE interpretations, Delgrande et al. (2008. Proc. of the 11th International Conference on Principles of Knowledge Representation and Reasoning (KR'08), 411–421; 2013b. Proc. of the 12th International Conference on Logic Programming and Nonmonotonic Reasoning (LPNMR'13), 264–276) adapted the well-known AGM framework (Alchourrón et al. 1985. Journal of Symbolic Logic 50, 2, 510–530) to LP revision. They identified the rational behavior of LP revision and introduced some specific operators. In this paper, a constructive characterization of all rational LP revision operators is given in terms of orderings over propositional interpretations with some further conditions specific to SE interpretations. It provides an intuitive, complete procedure for the construction of all rational LP revision operators and makes easier the comprehension of their semantic and computational properties. We give a particular consideration to LPs of very general form, i.e., the generalized logic programs (GLPs). We show that every rational GLP revision operator is derived from a propositional revision operator satisfying the original AGM postulates. Interestingly, the further conditions specific to GLP revision are independent from the propositional revision operator on which a GLP revision operator is based. Taking advantage of our characterization result, we embed the GLP revision operators into structures of Boolean lattices, that allow us to bring to light some potential weaknesses in the adapted AGM postulates. To illustrate our claim, we introduce and characterize axiomatically two specific classes of (rational) GLP revision operators which arguably have a drastic behavior. We additionally consider two more restricted forms of LPs, i.e., the disjunctive logic programs (DLPs) and the normal logic programs (NLPs) and adapt our characterization result to disjunctive logic program and normal logic program revision operators.


1969 ◽  
Vol 10 (3) ◽  
pp. 235-238 ◽  
Author(s):  
William C. Nemitz
Keyword(s):  

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1387 ◽  
Author(s):  
Pavel Trojovský

In 2008, I. Włoch introduced a new generalization of Pell numbers. She used special initial conditions so that this sequence describes the total number of special families of subsets of the set of n integers. In this paper, we prove some results about the roots of the characteristic polynomial of this sequence, but we will consider general initial conditions. Since there are currently several types of generalizations of the Pell sequence, it is very difficult for anyone to realize what type of sequence an author really means. Thus, we will call this sequence the generalized k-distance Tribonacci sequence (Tn(k))n≥0.


1976 ◽  
Vol 21 (2) ◽  
pp. 234-240
Author(s):  
Richard D. Byrd ◽  
Roberto A. Mena

A chain C in a distributive lattice L is called strongly maximal in L if and only if for any homomorphism φ of L onto a distributive lattice K, the chain (Cφ)0 is maximal in K, where (Cφ)0 = Cφ if 0 ∉ K, and (Cφ)0 = Cφ ∪ {0}, otherwise. Gratzer (1971, Theorem 28) states that if B is a generalized Boolean lattice R-generated by L and C is a chain in L, then C R-generates B if and only if C is strongly maximal in L. In this note (Theorem 4.6), we prove the following assertion, which is not far removed from Gratzer's statement: let B be a generalized Boolean lattice R-generated by L and C be a chain in L. If 0 ∈ L, then C generates B if and only if C is strongly maximal in L. If 0 ∉ L, then C generates B if and only if C is strongly maximal in L and [C)L = L. In Section 5 (Example 5.1) a counterexample to Gratzer's statement is provided.


2003 ◽  
Vol 49 (4) ◽  
pp. 394-400
Author(s):  
Stefano Leonesi ◽  
Carlo Toffalori
Keyword(s):  

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