Glossary entry

English term or phrase:

stalling

Russian translation:

вырожденные итерации (приводящие к запаздыванию результатов при выполнении симплекс-метода ).

Added to glossary by *Alena*
Nov 15, 2014 16:26
9 yrs ago
English term

stalling

English to Russian Science Mathematics & Statistics
So if this objective it was z, there are, or we change it to z plus x, you may still get the same theme final vertex, but you may get different sequence of dictionaries. On a problem to problem basis you can always run simplex and find out. But, the one message to take away is the reason that *stalling* occurs.
And, *stalling* occurs because in higher dimensions it's much more common to encounter this kind of
degeneracy where multiple faces, more than n faces meet at the vertex and give rise to a large number of dictionaries. Hopefully this is all clear and if so, we'll talk about Unbounded Polyhedra and Rays.
Change log

Nov 18, 2014 14:00: *Alena* changed "Edited KOG entry" from "<a href="/profile/1200982">*Alena*'s</a> old entry - "stalling"" to ""вырожденные итерации (при выполнении симплекс-метода, приводят к запаздыванию результатов.)""

Nov 18, 2014 14:00: *Alena* changed "Edited KOG entry" from "<a href="/profile/1200982">*Alena*'s</a> old entry - "stalling"" to ""вырожденные итерации (при выполнении симплекс-метода приводят к запаздыванию результатов.)""

Nov 18, 2014 14:04: *Alena* changed "Edited KOG entry" from "<a href="/profile/1200982">*Alena*'s</a> old entry - "stalling"" to ""вырожденные итерации (при выполнении симплекс-метода приводят к запаздыванию результатов).""

Discussion

DLyons Nov 16, 2014:
@Alena Cycling can be eliminated e.g. by http://en.wikipedia.org/wiki/Bland's_rule

Stalling is less serious in that progress is eventually made but, as far as I know, can't be eliminated.

You'd really need a printed book to decide :-)

Хемди А. Таха Глава 3. Симплекс-метод // Введение в исследование операций = Operations Research: An Introduction. — 7-е изд. — М.: «Вильямс», 2007. — С. 95-141. — ISBN 0-13-032374-8.
Акулич И.Л. Глава 1. Задачи линейного программирования // Математическое программирование в примерах и задачах. — М.: Высшая школа, 1986. — 319 с. — ISBN 5-06-002663-9.
Томас Х. Кормен и др. Глава 29. Линейное программирование // Алгоритмы: построение и анализ = INTRODUCTION TO ALGORITHMS. — 2-е изд. — М.: «Вильямс», 2006. — С. 1296. — ISBN 5-8459-0857-4.
В. Н. Шевченко, Н. Ю. Золотых Линейное и целочисленное линейное программирование. — Нижний Новгород: Издательство Нижегородского госуниверситета им. Н.И. Лобачевского, 2004. — С. 63-66 (раздел 2.8. Замечания о сложности решения ЗЛП).
*Alena* (asker) Nov 16, 2014:
Really, it must be less serious, stalling stays at the same basic solution although changing bases for several iterations, before moving to the next solution. I wanted запаздывание. Вырожденные итерации sounds even more exact, if I understand everything correctly. But google doesn't confirm anything in Russian, it finds only зацикливание. Should I follow the rules or be brave?
Some more context: All we know is that one of these dictionaries, one of the 20, or at least one of the 20, is final. So, therefore, what simplex is going to do is, in one step, it's going to achieve the optimal solution, but it doesn't know about it. So, it can stall in the worst case for up to 20 steps. Go through each and every one of these dictionaries here, before you get to a final dictionary, and stop. And, that can happen, okay? And, polyhedra where these can happen are highly degenerate polyhedra. And, they can be constructed, they're not hard to construct. And, you can make the *stalling problem* for simplex really bad. In general it's very hard to predict.

Proposed translations

33 mins
Selected

вырожденных итераций

Degenerate iterations. Not quite as serious as "cycling"= зацикливания.

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Note added at 42 mins (2014-11-15 17:08:41 GMT)
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Or почти вырожденными

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Note added at 19 hrs (2014-11-16 11:58:20 GMT)
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I'm not sure that the Russian literature makes a clear distinction between cycling and stalling e.g.
"Так вот при большой размерности матрицы, порядка 20 строк на 100 столбцов, симплекс начинает зацикливаться. В одной книге прочитал, что можно бороться с зацикливанием с помощью модификации симплекс-метода: лексикографический симплекс-метод. Немного переписал программу как было написано в книге. Стало меньше зацикливаться, но полностью не прекратилось."
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4 KudoZ points awarded for this answer. Comment: "Спасибо. :)"
22 hrs

замедление

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Note from asker:
И Вам спасибо, Ник.
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