Finite Projective Distributive Lattices
Canadian mathematical bulletin, Tome 13 (1970) no. 1, pp. 139-140
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The theorem stated below is due to R. Balbes. The present proof is direct; it uses only the following two well-known facts: (i) Let K be a category of algebras, and let free algebras exist in K; then an algebra is projective if and only if it is a retract of a free algebra, (ii) Let F be a free distributive lattice with basis {x i | i ∊ I}; then ∧(x i | i ∊ J 0) ≤ ∨(x i | i ∊ J 1) implies J 0∩J 1≠φ. Note that (ii) implies (iii): If for J 0 ⊆ I, a, b ∊ F, ∧(x i | i ∊ J 0)≤a ∨ b, then ∧ (x i | i ∊ J 0)≤ a or b.
Grätzer, G.; Wolk, B. Finite Projective Distributive Lattices. Canadian mathematical bulletin, Tome 13 (1970) no. 1, pp. 139-140. doi: 10.4153/CMB-1970-030-0
@article{10_4153_CMB_1970_030_0,
author = {Gr\"atzer, G. and Wolk, B.},
title = {Finite {Projective} {Distributive} {Lattices}},
journal = {Canadian mathematical bulletin},
pages = {139--140},
year = {1970},
volume = {13},
number = {1},
doi = {10.4153/CMB-1970-030-0},
url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1970-030-0/}
}
[(2)] (2) Pacific J. Math. 21 (1967), 405-420.
[(3)] (3) The map φ is by necessity the same as in R. Balbes, loc. cit.
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