Changes between Initial Version and Version 9 of Ticket #28237
 Timestamp:
 07/26/19 16:53:57 (3 years ago)
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Ticket #28237

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new
toneeds_review

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Authors
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Galen DorpalenBarry, Bryan Gillespie, Jacob P. Matherne, Thomas McConville, Franco Saliola

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PLEASE CHANGE
tocombinatorics

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Summary
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Atkinson's algorithm for counting linear extensions of (tree) posets
toImplement Atkinson's algorithm for counting linear extensions of (tree) posets
 Property Owner changed from (none) to jmatherne

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u/jmatherne/atkinson_s_algorithm_for_counting_linear_extensions_of__tree__posets
 Property Keywords IMA Coding Sprints days99 linear extensions posets trees spectrum added

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fd63ff1f5e32c68a8cedca4a6fdcd81b02f353ce

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toenhancement

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Ticket #28237 – Description
initial v9 1 We add two methods to posets.py: 2 3  "spectrum"  This method has input a poset `P` and an element `a` of `P`. It outputs the `a`spectrum of `P`, which is a list of integers whose ith entry contains the number of linear extensions of `P` with `a` in the ith position. In particular, the sum of the entries of the `a`spectrum is the number of linear extensions of `P`. 4 5  "atkinson"  This method has input a poset `P`, whose underlying undirected graph is a forest, and an element `a` of `P`. It uses Atkinson's algorithm (see reference below) to compute the `a`spectrum of `P` (see definition of `a`spectrum above). 6 7 M. D. Atkinson, ''On computing the number of linear extensions of a tree'', Order '''7''' (1990), 2325.