A note on two Erdősʼs proofs of the infinitude of primes

P. Erdős found numerous theorems, problems, results and conjectures in elementary number theory. Some of them are two Erdősʼs proofs of of the famous Euclidʼs theorem on the infinitude of primes. As noticed below, one of these proofs immediately implies the fact that the number of primes smaller than x is $⩾\log x/(2\log 2)$.     

Waring-Goldbach problems for unlike powers with almost equal variables

We prove that almost all positive even integers n can be written as n=p22+p33+p44+p55 with |pkk-N4|≤N321325+? for 2≤k≤5. Moreover, it is proved that each sufficiently large odd integer N can be represented as N=p1+p22+p33+p44+p55 with |pkk-N5|≤N321325+?for 1≤k≤5.     

关于奇数Goldbach问题

本文通过Ｌ函数非零区域的扩张及相应的素数分布均值问题的研究证明了：每一个奇数Ｎ≥ｅｘｐ（ｅｘｐ（９．７１５））都能够表示成为三个素数之和．     

On prime submodules and primary decomposition

We characterize prime submodules of R × R for a principal ideal domain R and investigate the primary decomposition of any submodule into primary submodules of R × R.     

Almost-all results on the <Emphasis Type=”Italic”>p</Emphasis><Superscript>&;#955;</Superscript> problem

Summary  We describe a procedure to construct a 4-coloured graph representing a closed, connected 3-manifold Italic>M starting from a Heegaard diagram of Italic>M. As a consequence, we prove that, to each Heegaard diagram of a (closed) 3-manifold Italic>M, canonically corresponds a spine (Italic>Heegaard spine) of Italic>M.     

Solutions of the congruence

To supplement existing data, solutions of are tabulated for primes with and . For , five new solutions 2^{32}$"> are presented. One of these, for , also satisfies the ``reverse' congruence . An effective procedure for searching for such ``double solutions' is described and applied to the range , . Previous to this, congruences are generally considered for any and fixed prime to see where the smallest prime solution occurs.

     

Laced Boolean functions and subset sum problems in finite fields

In this paper, we investigate some algebraic and combinatorial properties of a special Boolean function on n variables, defined using weighted sums in the residue ring modulo the least prime p≥n. We also give further evidence relating to a question raised by Shparlinski regarding this function, by computing accurately the Boolean sensitivity, thus settling the question for prime number values p=n. Finally, we propose a generalization of these functions, which we call laced functions, and compute the weight of one such, for every value of n.