377 research outputs found
Numerical study of the derivative of the Riemann zeta function at zeros
The derivative of the Riemann zeta function was computed numerically on
several large sets of zeros at large heights. Comparisons to known and
conjectured asymptotics are presented.Comment: 13 pages, 5 figures; minor typos fixe
The zeta function on the critical line: Numerical evidence for moments and random matrix theory models
Results of extensive computations of moments of the Riemann zeta function on
the critical line are presented. Calculated values are compared with
predictions motivated by random matrix theory. The results can help in deciding
between those and competing predictions. It is shown that for high moments and
at large heights, the variability of moment values over adjacent intervals is
substantial, even when those intervals are long, as long as a block containing
10^9 zeros near zero number 10^23. More than anything else, the variability
illustrates the limits of what one can learn about the zeta function from
numerical evidence.
It is shown the rate of decline of extreme values of the moments is modelled
relatively well by power laws. Also, some long range correlations in the values
of the second moment, as well as asymptotic oscillations in the values of the
shifted fourth moment, are found.
The computations described here relied on several representations of the zeta
function. The numerical comparison of their effectiveness that is presented is
of independent interest, for future large scale computations.Comment: 31 pages, 10 figures, 19 table
Exact asymptotics of monomer-dimer model on rectangular semi-infinite lattices
By using the asymptotic theory of Pemantle and Wilson, exact asymptotic
expansions of the free energy of the monomer-dimer model on rectangular lattices in terms of dimer density are obtained for small values
of , at both high and low dimer density limits. In the high dimer density
limit, the theoretical results confirm the dependence of the free energy on the
parity of , a result obtained previously by computational methods. In the
low dimer density limit, the free energy on a cylinder
lattice strip has exactly the same first terms in the series expansion as
that of infinite lattice.Comment: 9 pages, 6 table
On the existence of optimum cyclic burst-correcting codes
It is shown that for each integer b >= 1 infinitely many optimum cyclic b-burst-correcting codes exist, i.e., codes whose length n, redundancy r, and burst-correcting capability b, satisfy n = 2^{r-b+1} - 1. Some optimum codes for b = 3, 4, and 5 are also studied in detail
The Asymptotic Number of Irreducible Partitions
A partition of [1, n] = {1,..., n} is called irreducible if no proper subinterval of [1, n] is a union of blocks. We determine the asymptotic relationship between the numbers of irreducible partitions, partitions without singleton blocks, and all partitions when the block sizes must lie in some specified set
Scale invariant correlations and the distribution of prime numbers
Negative correlations in the distribution of prime numbers are found to
display a scale invariance. This occurs in conjunction with a nonstationary
behavior. We compare the prime number series to a type of fractional Brownian
motion which incorporates both the scale invariance and the nonstationary
behavior. Interesting discrepancies remain. The scale invariance also appears
to imply the Riemann hypothesis and we study the use of the former as a test of
the latter.Comment: 13 pages, 8 figures, version to appear in J. Phys.
An Optimal Acceptance Policy for an Urn Scheme
An urn contains m balls of value -1 and p balls of value +1. At each turn a ball is drawn randomly, without replacement, and the player decides before the draw whether or not to accept the ball, i.e., the bet where the payoff is the value of the ball. The process continues until all m+p balls are drawn. Let V(m,p) denote the value of this acceptance (m,p) urn problem under an optimal acceptance policy. In this paper, we first derive an exact closed form for V(m,p) and then study its properties and asymptotic behavior. We also compare this acceptance (m,p) urn problem with the original (m,p) urn problem which was introduced by Shepp [Ann. Math. Statist., 40 (1969), pp. 993--1010]. Finally, we briefly discuss some applications of this acceptance (m,p) urn problem and introduce a Bayesian approach to this optimal stopping problem. Some numerical illustrations are also provided
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