{% if Art01 %} ✏️ Modifier cette page {% endif %} Explicit bounds on primes ========================= .. if-builder:: html .. toctree:: :maxdepth: 2 Collecting references: :cite:`Dusart98`, :cite:`Dusart16` 1. Bounds on primes, in special ranges -------------------------------------- The paper :cite:`Rosser-Schoenfeld62`, contains several bounds valid only when the variable is small enough. These are proved by direction verifications. Different direct computations can be used to get effect in limited range. Here is a typical result. .. admonition:: Theorem (:cite:`Buthe16`) :class: thm-tme-emt Assume the Riemann Hypothesis has been checked up to height :math:`H_0`. Then when :math:`x` satisfies :math:`\sqrt{x/\log x}\le H_0/4.92`, we have * :math:`|\psi(x)-x|\le \frac{\sqrt{x}}{8\pi}\log^2x` when :math:`x > 59`, * :math:`|\theta(x)-x|\le \frac{\sqrt{x}}{8\pi}\log^2x` when :math:`x > 599`, * :math:`|\pi(x)-\text{li}(x)|\le \frac{\sqrt{x}}{8\pi}\log x` when :math:`x > 2657`. If we use the value :math:`H_0=3 \cdot 10^{12}` obtained by Platt and Trudgian in :cite:`Platt-Trudgian21a` (which improves previous results in :cite:`Platt17` ), these bounds are thus valid for :math:`x\le 2.16\cdot 10^{25}`. In :cite:`Buthe18` the following bounds are also obtained. .. admonition:: Theorem (2018) :class: thm-tme-emt We have * :math:`|\psi(x)-x|\le 0.94\sqrt{x}` when :math:`11 < x\le 10^{19}`, * :math:`0<\text{li}(x)-\pi(x)\le\frac{\sqrt{x}}{\log x}\Bigl(1.95+\frac{3.9}{\log x}+\frac{19.5}{\log^2x}\Bigr)` when :math:`2\le x\le 10^{19}`. 2. Bounds on primes, without any congruence condition ----------------------------------------------------- The subject really started with the four papers :cite:`Rosser41`, :cite:`Rosser-Schoenfeld62`, :cite:`Rosser-Schoenfeld75` and :cite:`Schoenfeld76`. We recall the usual notation: :math:`\pi(x)` is the number of primes up to :math:`x` (so that :math:`\pi(3)=2`), the function :math:`\psi(x)` is the summatory function of the van Mangold function :math:`\Lambda`, i.e. :math:`\psi(x)=\sum_{n\le x}\Lambda(n)`, while we also define :math:`\vartheta(x)=\sum_{p\le x}\log p`. Here are some elegant bounds that one can find in those papers. .. admonition:: Theorem (1962) :class: thm-tme-emt * For :math:`x > 0`, we have :math:`\psi(x)\le 1.03883 x` and the maximum of :math:`\psi(x)/x` is attained at :math:`x=113`. * When :math:`x\ge17`, we have :math:`\pi(x) > x/\log x`. * When :math:`x > 1`, we have :math:`\displaystyle \sum_{p\le x}1/p > \log\log x`. * When :math:`x > 1`, we have :math:`\displaystyle \sum_{p\le x}(\log p)/p < \log x`. There are many other results in those papers. In :cite:`Dusart99-1` , one can find among other things the inequality .. raw:: html