id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
17252,bug fix in StrongTableaux.marked_CST_to_transposition_sequence,zabrocki,,"Anne Schilling pointed out the following error in the algorithm to convert a strong marked column strict tableau to a sequence of transpositions:
{{{
sage: StrongTableaux.marked_CST_to_transposition_sequence([[-1,-2,-2,-2,-2],[-2,2],[2]],3)
[[4, 5], [3, 4], [2, 4], [2, 3], [1, 2], [0, 1]]
}}}
however the answer should be `[[4,5],[3,4],[2,3],[1,2],[-1,0],[0,1]]` and the problem arises because it was never clear in the algorithm for converting a marked column strict tableau into a sequence of transpositions what conditions I need to check to make sure I was applying a valid transposition. In fact, there was a comment in the code that indicated my worry that one might be able to apply two transpositions and reduce the length by 1.
This is exactly what happens in this case because if you apply the sequence of transpositions t_{2,4} on t_{3,4} t_{4,5} T then in fact t_{2,4} does reduce the length of shape of the tableau by 1, but there are no cells of content 2 and 3 in the tableau t_{3,4} t_{4,5} T.
The fix was to implement the method `to_transposition_sequence` recursively by checking that the result of applying `t_{i,j}` can reduced to the empty core.",defect,closed,major,sage-6.4,combinatorics,fixed,tableaux,aschilling tscrim,,Mike Zabrocki,Anne Schilling,N/A,,381acd835802d712e3a4a7ba547c7aeb2393b94a,381acd835802d712e3a4a7ba547c7aeb2393b94a,,