In this paper, the authors propose a new chaotic block cryptosystem based on multiple one-dimensional chaotic maps. In the proposed cryptosystem, the authors establish map-to-task relations between the multiple chaotic maps and the tasks, which must be performed in the encryption rounds. The encryption process is based on these map-to-task relations. The authors enhance the security of the cryp...

The main objective of this work is to exploit the relationship between the information findability problem and a subject-based organization of information. Identification of a subject is involved when one wants to say something about that subject or when he or she tries to comprehend what was said by others about it. An example of this type of duality can be seen in the information world where ...

The aim of this paper is to prove the following results: a continuous map f : [0, 1]→ [0, 1] is chaotic iff the shift map σf : lim ← ([0, 1], f)→ lim ← ([0, 1], f) is chaotic. However, this result fails, in general, for arbitrary compact metric spaces. σf : lim ← ([0, 1], f) → lim ← ([0, 1], f) is chaotic iff there exists an increasing sequence of positive integers A such that the topological s...

Concern for environmental issues has become a reality in all sectors of society, mainly among researchers and professionals who work directly with environmental status. In this context, several studies have been undertaken on sustainable development of the Brazilian Amazon, generating a large amount of data and information. Environmental area characterization involves the knowledge about their ...

This paper discusses the geometric correction of measured historical maps and the evaluation of accuracy with case studies on Silk Road maps, “Innermost Asia” and “Serindia,” made by Aurel Stein about 100 years ago, and Beijing maps, “Complete map of Peking, Qianlong period,” made about 250 years ago. The former case study deals with maps that cover thousand kilometers, and we delivered the err...

In this paper, some categorical properties of the category ${bf Cpo}_{{bf Act}text{-}S}$ of all {cpo $S$-acts}, cpo's equipped with actions of a monoid $S$ on them, and strict continuous action-preserving maps between them is considered. In particular, we describe products and coproducts in this category, and consider monomorphisms and epimorphisms. Also, we show that the forgetful functor from...

This paper is concerned with the best proximity pair problem in Hilbert spaces. Given two subsets $A$ and $B$ of a Hilbert space $H$ and the set-valued maps $F:A o 2^ B$ and $G:A_0 o 2^{A_0}$, where $A_0={xin A: |x-y|=d(A,B)~~~mbox{for some}~~~ yin B}$, best proximity pair theorems provide sufficient conditions that ensure the existence of an $x_0in A$ such that $$d(G(x_0),F(x_0))=d(A,B).$$