bio | website | TheBigQuestions.com/blog |
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Jul 23 |
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Worst case difference in rank by column-row swapping
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Jul 23 |
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Worst case difference in rank by column-row swapping
@BrendanMcKay: Actually, I'm back to not being sure what "swapping" means, so the operation might be as in my comment or as above. Fortunately, the above argument works either way. I've included an edit to mention this. |
Jul 23 |
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Worst case difference in rank by column-row swapping
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Jul 23 |
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Worst case difference in rank by column-row swapping
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Jul 22 |
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Worst case difference in rank by column-row swapping
I've deleted my last comment, which was nonsense. |
Jul 9 |
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the true reason of the incompleteness of formal systems
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Jul 9 |
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Worst case difference in rank by column-row swapping
@BrendanMcKay: The operation seems to be $$\pmatrix{A&B\cr C&D\cr}\mapsto \pmatrix {A&C^T\cr B^T&D\cr}$$ where $A$ and $D$ are square matrices (perhaps of different sizes), $C$ and $D$ are rectangular of appropriate sizes, and the upper-$T$ denotes the transpose. |
Jul 9 |
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Worst case difference in rank by column-row swapping
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Jul 9 |
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Worst case difference in rank by column-row swapping
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Jul 9 |
answered | Worst case difference in rank by column-row swapping |
Jul 7 |
awarded | Good Answer |
Jul 5 |
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Which journals publish research announcements?
@SergeiAkbarov: A "research announcement" is a short communication without complete proofs. |
Jul 5 |
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Worst case difference in rank by column-row swapping
Ah. I see that you've changed your example to respond to my last comment, but without bothering to mention or acknowledge it. |
Jul 5 |
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Worst case difference in rank by column-row swapping
Your example adds to my confusion. If $S_i$ is the operation that "swaps" the $i$th row and column, and if I understand what "swap" means, then it seems that the $S_i$ commute with each other. But your example suggests that the results of applying $S_iS_j$ and $S_jS_i$ are different. So I'm back to believing that I don't know what "swap" means. |
Jul 5 |
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Worst case difference in rank by column-row swapping
What does it mean to swap rows for columns? In particular, what is the result of swapping the first row for the second column in $\pmatrix{a&b\cr c&d\cr}$ ? |
Jul 4 |
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Freedom of speech in scientific discussions - An invitation to more tolerance in Scientific debates
This is not a math question. |
Jun 29 |
awarded | Nice Answer |
May 25 |
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John Nash's Mathematical Legacy
@IgorKhavkine: I'm the wrong person to ask. |
May 24 |
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John Nash's Mathematical Legacy
@IgorKhavkine: The paper is basically a list of desiderata for a parellel computer. |
May 14 |
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Second differences of primes determined by increasing first differences: every positive even integer?
@JonMarkPerry: It would really be better if you answered the question. |