Congruence modularity implies the Arguesian identity

1976 ◽  
Vol 6 (1) ◽  
pp. 225-228 ◽  
Author(s):  
Ralph Freese ◽  
Bjarni Jónsson
2011 ◽  
Vol 66 (1-2) ◽  
pp. 63-67
Author(s):  
Benedek Skublics

1977 ◽  
Vol 7 (1) ◽  
pp. 191-194 ◽  
Author(s):  
Ralph Freese ◽  
J. B. Nation

1990 ◽  
Vol 41 (2) ◽  
pp. 283-300 ◽  
Author(s):  
Ralph McKenzie

Corresponding to each ordered set there is a variety, determined up to equivalence, generated by an algebra whose term operations are all the monotone operations on the ordered set. We produce several characterisations of the finite bounded ordered sets for which the corresponding variety is congruence-distributive. In particular, we find that congruence-distributivity, congruence-modularity, and residual smallness are equivalent for these varieties.


1980 ◽  
Vol 32 (5) ◽  
pp. 1140-1167 ◽  
Author(s):  
Alan Day ◽  
Ralph Freese

In his thesis and [24], J. B. Nation showed the existence of certain lattice identities, strictly weaker than the modular law, such that if all the congruence lattices of a variety of algebras satisfy one of these identities, then all the congruence lattices were even modular. Moreover Freese and Jónsson showed in [10] that from this “congruence modularity” of a variety of algebras one can even deduce the (stronger) Arguesian identity.These and similar results [3; 5; 9; 12; 18; 21] induced Jónsson in [17; 18] to introduce the following notions. For a variety of algebras , is the (congruence) variety of lattices generated by the class () of all congruence lattices θ(A), . Secondly if is a lattice identity, and Σ is a set of such, holds if for any variety implies .


1976 ◽  
Vol 6 (1) ◽  
pp. 291-301 ◽  
Author(s):  
Alan Day

2006 ◽  
Vol 55 (4) ◽  
pp. 495-508 ◽  
Author(s):  
Luís Sequeira

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