On principal congruences and the number of congruences of a lattice with more ideals than filters
Let λ and κ be cardinal numbers such that κ is infinite and either 2 ≤ λ ≤ κ , or λ = 2 κ . We prove that there exists a lattice L with exactly λ many congruences, 2 κ many ideals, but only κ many filters. Furthermore, if λ ≥ 2 is an integer of the form 2 m · 3 n , then we can choose L to be a modul...
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Veröffentlicht in: | Acta scientiarum mathematicarum (Szeged) 2019-01, Vol.85 (3-4), p.363-380 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Let λ and
κ
be cardinal numbers such that
κ
is infinite and either 2 ≤ λ ≤
κ
, or λ = 2
κ
. We prove that there exists a lattice L with exactly λ many congruences, 2
κ
many ideals, but only
κ
many filters. Furthermore, if λ ≥ 2 is an integer of the form 2
m
· 3
n
, 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 2
κ
many ideals, but (iv)
L
has only
κ
many filters. |
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ISSN: | 0001-6969 2064-8316 |
DOI: | 10.14232/actasm-018-538-y |