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Difference between revisions of "Length of a partially ordered set"

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(cite Grätzer (2003))
(Dilworth's lemma, cite Dilworth (1950))
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The greatest possible length of a [[chain]] (totally ordered subset) in a [[partially ordered set]] (the length of a finite chain is one less than the number of elements). There exist infinite partially ordered sets of finite length.  A partially order set of length zero is a [[trivial order]].
 
The greatest possible length of a [[chain]] (totally ordered subset) in a [[partially ordered set]] (the length of a finite chain is one less than the number of elements). There exist infinite partially ordered sets of finite length.  A partially order set of length zero is a [[trivial order]].
  
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Dilworth's theorem [[#References|[1]]] states that in a finite partially ordered set the length is equal to the minimal number of [[anti-chain]]s (sets of mutually incompable elements) that cover the set.
  
 
====References====
 
====References====
* George Grätzer, ''General Lattice Theory'', Springer (2003) ISBN 3764369965
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<table>
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<TR><TD valign="top">[1]</TD> <TD valign="top">  R.P. Dilworth,  "A decomposition theorem for partially ordered sets"  ''Ann. of Math.'' , '''51'''  (1950)  pp. 161–166</TD></TR>
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<TR><TD valign="top">[2]</TD> <TD valign="top">  George Grätzer, ''General Lattice Theory'', Springer (2003) ISBN 3764369965</TD></TR>
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</table>

Revision as of 22:04, 6 December 2014

2020 Mathematics Subject Classification: Primary: 06A [MSN][ZBL]

The greatest possible length of a chain (totally ordered subset) in a partially ordered set (the length of a finite chain is one less than the number of elements). There exist infinite partially ordered sets of finite length. A partially order set of length zero is a trivial order.

Dilworth's theorem [1] states that in a finite partially ordered set the length is equal to the minimal number of anti-chains (sets of mutually incompable elements) that cover the set.

References

[1] R.P. Dilworth, "A decomposition theorem for partially ordered sets" Ann. of Math. , 51 (1950) pp. 161–166
[2] George Grätzer, General Lattice Theory, Springer (2003) ISBN 3764369965
How to Cite This Entry:
Length of a partially ordered set. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Length_of_a_partially_ordered_set&oldid=35429
This article was adapted from an original article by T.S. Fofanova (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article