The problem of the existence of infinitely many prime values of a number-theoretic function f (x) has been one of the most important topics in Number Theory. Note that if f (x) represents infinitely many primes, then we can get this necessary condition: for any positive integer h , there exists a positive integer k such that ( f (k), h) =1and f (k) >1. Naturally, we are interested in the number-theoretic functions f (x) that satisfy the aforementioned necessary condition. Thus, there must exist the least positive integer n such that (f(n),h)-1andf(k)>1. Denote this least positive integer n byF_f(h). In this paper, we mainly focus on three famous number-theoretic functions:&f(x)=2^{2^x}+1,m(x)=2^x-1 and l(x)=x^2+1& proving they satisfy the aforementioned necessary condition respectively. Furthermore, we approximately estimate the upper bound of F_f(x)(h),Fm(x)(h)，Fl(x)(h) respectively, and obtain some interesting results.

It is well known that del Pezzo surfaces of degree 9 − n one-to-one correspond to flat En bundles over an elliptic curve. In this paper, we construct ADE-bundles over a broader class of rational surfaces that we call ADE-surfaces, and extend the above correspondence to all flat G-bundles over an elliptic curve, where G is any simply laced, simple, compact and simply connected Lie group. In what follows, we will construct G-bundles for a non-simply laced Lie group G over these rational surfaces, and extend the above correspondence to non-simply laced cases.

No abstract uploaded!

No abstract uploaded!

In previous work, the notion of Mixed-Spin-P(MSP) fields is introduced and their moduli space is constructed together with a torus action. By applying virtual localization to their virtual classes moduli of MSP fields, polynomial relations among Gromov Witten(GW) and Fan-Jarvis-Ruan-Witten(FJRW) invariants of Fermat quintics are derived. In this paper, we prove a vanishing of a class of torus-fixed loci. This vanishing plays a key role in later proof that in Witten's gauged linear sigma model for Fermat quintics, the FJRW invariants with insertions 2/5 determine the GW invariants of quintic Calabi-Yau threefolds through CY-LG phase transitions.