On principal congruences and the number of congruences of a lattice with more ideals than filters

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作者
Gábor Czédli
Claudia Mureşan
机构
[1] University of Szeged,Bolyai Institute
[2] Faculty of Mathematics and Computer Science of the University of Bucharest,undefined
[3] Università degli Studi di Cagliari,undefined
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06B10; lattice ideal; lattice filter; simple lattice; more ideals than filters; number of ideals; cardinality; lattice congruence; principal congruence;
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摘要
Let λ and κ be cardinal numbers such that κ is infinite and either 2 ≤ λ ≤ κ, or λ = 2κ. We prove that there exists a lattice L with exactly λ many congruences, 2κ many ideals, but only κ many filters. Furthermore, if λ ≥ 2 is an integer of the form 2m · 3n, then we can choose L to be a modular lattice generating one of the minimal modular nondistributive congruence varieties described by Ralph Freese in 1976, and this L is even relatively complemented for λ = 2. Related to some earlier results of George Grätzer and the first author, we also prove that if P is a bounded ordered set (in other words, a bounded poset) with at least two elements, G is a group, and κ is an infinite cardinal such that κ ≤ |P| and κ ≤ |G|, then there exists a lattice L of cardinality κ such that (i) the principal congruences of L form an ordered set isomorphic to P, (ii) the automorphism group of L is isomorphic to G, (iii) L has 2κ many ideals, but (iv) L has only κ many filters.
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页码:363 / 380
页数:17
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