Certificateless cryptography eliminates the need of certificacates in the public key crytosystems and solves the inherent key escrow problem in identity-based cryptosystems. This paper demonstrates that two certificateless signature schemes proposed by Guo et al. and Wang et al. respectively are insecure against key replacement attacks by a type I adversary. We show that the adversary who can replace a signer's public key can forge signatures under the replaced public key. We then make a suggestion to prevent the attacks.

In this paper, we introduce the weak G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -expansivity which is a generalization of both expansivity and G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -expansivity. Also, we define G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -stable and G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -unstable sets of a homeomorphism on a metric G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -space X $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">X</span>}$ and investigate properties of them. Finally, we consider the decomposition theorem on G $\mathrm{<span\; style="font-family:\; 돋움;\; font-size:\; 11pt;">G</span>}$ -spaces.

The purpose of this work is to introduce a hybrid projection method for finding a common element of the set of a generalized equilibrium problem, the set of solutions to a variational inequality and the set of fixed points of a strict pseudo-contraction in a real Hilbert space.

In an infinite-dimensional Hilbert space, the normal Mann’s iteration algorithm has only weak convergence, in general, even for nonexpansive mappings. In order to get a strong convergence result, we modify the normal Mann’s iterative process for an infinite family of nonexpansive mappings in the framework of Banach spaces. Our results improve and extend the recent results announced by many others.

We investigate the six-state clock model with nearest-neighbor interactions on the square lattice. We obtain the density of states of the finite systems up to $L=28$ using the Wang-Landau sampling. With the density of states and the Fisher zero approach, we successfully find two different critical temperatures 0.632(2) and 0.997(2) for the clock model. It seems that this study supports the recent results by [Lapilli et al.Phys. Rev. Lett. 96, 140603 (2006)] that the transitions are not of Kosterlitz and Thouless type.

In this paper, we report our study on the minimised atomistic model (MAM) and the determination of an evolution path for dominant B _m I _n clusters during boron diffusion in kinetic Monte Carlo (KMC). It has been known that clusters generated after ion implantation play a decisive role in the enhanced boron diffusion at the tail region while being immobile at the peak region. Our MAM, based on the simple continuum model and the simple atomistic model, takes the smallest number of intermediate clusters into account as well as dominant clusters for the evolution path of interstitial clusters during boron diffusion. We find that intermediate clusters such as B₂I₃ and B₃I₃ play a significant role during the evolution of clusters despite the fact that the lifetimes of the corresponding intermediate clusters are relatively short due to low binding energies. Also, through our simulation results, we find the main evolution path of dominant clusters from B₂I to B₃I during thermal annealing in the MAM. Furthermore, our investigation reveals that the density of BI₂ clusters increases at the beginning of the annealing process while the density of B₃I increases at a later stage. KMC simulation results are compared with experimental SIMS data, which support our theoretical model.