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Frankl’s conjecture for large semimodular and planar semimodular lattices

Gábor Czédli, E. Tamás Schmidt (2008)

Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica

A lattice L is said to satisfy (the lattice theoretic version of) Frankl’s conjecture if there is a join-irreducible element f L such that at most half of the elements x of L satisfy f x . Frankl’s conjecture, also called as union-closed sets conjecture, is well-known in combinatorics, and it is equivalent to the statement that every finite lattice satisfies Frankl’s conjecture. Let m denote the number of nonzero join-irreducible elements of L . It is well-known that L consists of at most 2 m elements....

Luzin and anti-Luzin almost disjoint families

Judith Roitman, Lajos Soukup (1998)

Fundamenta Mathematicae

Under M A ω 1 every uncountable almost disjoint family is either anti-Luzin or has an uncountable Luzin subfamily. This fails under CH. Related properties are also investigated.

On 0 - 1 measure for projectors

Václav Alda (1980)

Aplikace matematiky

An example of a finite set of projectors in E 3 is exhibited for which no 0-1 measure exists.

On a weak Freudenthal spectral theorem

Marek Wójtowicz (1992)

Commentationes Mathematicae Universitatis Carolinae

Let X be an Archimedean Riesz space and 𝒫 ( X ) its Boolean algebra of all band projections, and put 𝒫 e = { P e : P 𝒫 ( X ) } and e = { x X : x ( e - x ) = 0 } , e X + . X is said to have Weak Freudenthal Property ( WFP ) provided that for every e X + the lattice l i n 𝒫 e is order dense in the principal band e d d . This notion is compared with strong and weak forms of Freudenthal spectral theorem in Archimedean Riesz spaces, studied by Veksler and Lavrič, respectively. WFP is equivalent to X + -denseness of 𝒫 e in e for every e X + , and every Riesz space with sufficiently many projections...

On fields and ideals connected with notions of forcing

W. Kułaga (2006)

Colloquium Mathematicae

We investigate an algebraic notion of decidability which allows a uniform investigation of a large class of notions of forcing. Among other things, we show how to build σ-fields of sets connected with Laver and Miller notions of forcing and we show that these σ-fields are closed under the Suslin operation.

On minimal spectrum of multiplication lattice modules

Sachin Ballal, Vilas Kharat (2019)

Mathematica Bohemica

We study the minimal prime elements of multiplication lattice module M over a C -lattice L . Moreover, we topologize the spectrum π ( M ) of minimal prime elements of M and study several properties of it. The compactness of π ( M ) is characterized in several ways. Also, we investigate the interplay between the topological properties of π ( M ) and algebraic properties of M .

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