Kevin O'Bryant
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Registered User
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Research: additive number theory; combinatorial number theory.
Faculty at City University of New York, at the Staten Island and Graduate Center campuses.
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May 14 |
revised |
two boy scouts problems added link to wikipedia |
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Apr 8 |
awarded | ● Nice Answer |
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Mar 20 |
awarded | ● Nice Answer |
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Mar 12 |
comment |
From reducible polynomial to an irreducible one This is a ring (just not one with unity). In any case, the OP asked for "an algebraic construction". |
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Mar 7 |
answered | From reducible polynomial to an irreducible one |
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Feb 19 |
comment |
Most inconsistent ranking Call the matrix $M=(m_{ij})$. Then, if I understand correctly, ``total sum of the variance of each row'' is defined to be $\sum_{i=1}^k \frac1n \sum_{j=1}^n (m_{ij}-\frac 1n \sum_{\ell=1}^n m_{i\ell})^2$. |
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Feb 19 |
revised |
Most inconsistent ranking changed sd to variance |
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Feb 19 |
revised |
Most inconsistent ranking added $k=3$ |
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Feb 19 |
answered | Most inconsistent ranking |
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Feb 12 |
awarded | ● Nice Answer |
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Jan 7 |
awarded | ● Good Answer |
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Jan 7 |
comment |
Have discovered a recursive formula for Prime Density - is this known? If you change "proof" to "argument", and change the question to "are there infinitely many $n$ where this underestimates the true density", and you'll avoid a closed question. |
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Jan 7 |
comment |
Have discovered a recursive formula for Prime Density - is this known? I get $D_3 = 4/15$ by your formula, but the actual density should be $6/23$. Through small values of $n$, I find that the actual density is about $0.01$ below your formula, but this is the sort of thing that small $n$ are misleading about. |
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Jan 5 |
comment |
Is pi a good random number generator? @Victor: Isn't that what "predictability" means? |
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Dec 28 |
revised |
Status of the 196 conjecture? Changed "Lycrel" to "Lychrel" |
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Dec 28 |
revised |
Status of the 196 conjecture? addressed a comment about the connection between f and s and palindromes |
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Dec 28 |
comment |
Status of the 196 conjecture? Typically, this sort of heuristic argument cannot be "fixed" because the underlying process is not random, but it can be improved. Aaron's answer explains some of the dependence, and one could try to bring that into this probabilistic model. One could then try and push the model to give the probability of, say, a 20 digit number having one of its first 50 iterates a palindrome. Such a probability can be compared to experiment as a way of assessing the heuristic. But to be clear: there is no chance that this will lead to a proof. |
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Dec 26 |
answered | Status of the 196 conjecture? |
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Dec 23 |
revised |
The origin of sets? added 191 characters in body |
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Dec 22 |
answered | The origin of sets? |
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Dec 20 |
comment |
unique sums in a finite direct product of sets of integers A more natural way to state the condition is that $|A_1+\cdots+A_h| = |A_1| \cdots |A_h|$ (the parameter $h$ is more common than $n$ here). These come up in additive combinatorics, but I don't know a name for them. If $A_1= \dots =A_h$, and you don't care about the ordering of the sum (i.e., one can reorder the $b_i$ so that $a_i=b_i$), these are called "Sidon Sets", also $B_h$-sets. |
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Dec 19 |
awarded | ● Nice Answer |
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Dec 19 |
answered | Publishing a bad paper? |
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Dec 4 |
awarded | ● Good Answer |
