Auxiliary solution-count conjectures for the discrete logarithm equation

About 22 years old · traced to

Let pp be prime. For the auxiliary equation studied in the paper, let Ch A,a B(p)C_{h\,A,a\,B}(p) denote the number of solutions with the indicated restrictions, and let ϕ\phi be Euler's totient function. If p−1p-1 is squarefree, write its prime divisors as qq; in general write qα∥p−1q^\alpha\Vert p-1 when qαq^\alpha is the exact power of qq dividing p−1p-1.

Auxiliary solution-count conjectures.

Ch ANY,a ANY(p)≈(p−1)+∑m∣p−1ϕ(m)m2(∑d∣(p−1)/mϕ(dm)d)2.C_{h\,\mathsf{ANY},a\,\mathsf{ANY}}(p)\approx (p-1)+\sum_{m\mid p-1}\frac{\phi(m)}{m^2}\left(\sum_{d\mid (p-1)/m}\frac{\phi(dm)}{d}\right)^2.

If p−1p-1 is squarefree, then

Ch ANY,a ANY(p)≈(p−1)+∏q∣p−1(q+1−1q).C_{h\,\mathsf{ANY},a\,\mathsf{ANY}}(p)\approx (p-1)+\prod_{q\mid p-1}\left(q+1-\frac1q\right).

In general,

Ch ANY,a ANY(p)≈(p−1)+∏qα∥p−1([(1−1q)α+1]2+(1−1q)3[(α+1)2qα+1−qq−1−2(α+1)αqα+2−(α+1)qα+1+q(q−1)2+α2qα+3−(2α2+2α−1)qα+2+(α2+2α+1)qα+1−q2−q(q−1)3]).C_{h\,\mathsf{ANY},a\,\mathsf{ANY}}(p)\approx (p-1)+\prod_{q^\alpha\Vert p-1}\left(\left[\left(1-\frac1q\right)\alpha+1\right]^2+\left(1-\frac1q\right)^3\left[(\alpha+1)^2\frac{q^{\alpha+1}-q}{q-1}-2(\alpha+1)\frac{\alpha q^{\alpha+2}-(\alpha+1)q^{\alpha+1}+q}{(q-1)^2}+\frac{\alpha^2q^{\alpha+3}-(2\alpha^2+2\alpha-1)q^{\alpha+2}+(\alpha^2+2\alpha+1)q^{\alpha+1}-q^2-q}{(q-1)^3}\right]\right).

The product is over primes qq dividing p−1p-1. Additionally,

Ch PR,a ANY(p)≈2ϕ(p−1),C_{h\,\mathsf{PR},a\,\mathsf{ANY}}(p)\approx 2\phi(p-1), Ch ANY,a PR(p)≈2ϕ(p−1),C_{h\,\mathsf{ANY},a\,\mathsf{PR}}(p)\approx 2\phi(p-1), Ch PR,a PR(p)≈ϕ(p−1)+ϕ(p−1)2p−1.C_{h\,\mathsf{PR},a\,\mathsf{PR}}(p)\approx \phi(p-1)+\frac{\phi(p-1)^2}{p-1}.

These predictions are derived from the paper's random-map heuristic for x↦xx mod px\mapsto x^x\bmod p and remain conjectural in the supplied text.

References

Primary source

Joshua Holden and Pieter Moree, “Some Heuristics and Results for Small Cycles of the Discrete Logarithm”, arXiv:math/0401013 (2004).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.