scholarly journals Integer Semigroups Associated with Dumont-Thomas Numeration Systems

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Víctor F. Sirvent

Given a primitive substitution, we define different binary operations on infinite subsets of the nonnegative integers. These binary operations are defined with the help of the Dumont-Thomas numeration system; that is, a numeration system associated with the substitution. We give conditions for these semigroups to have an identity element. We show that they are not finitely generated. These semigroups define actions on the set of positive integers. We describe the orbits of these actions. We also estimate the density of these sets as subsets of the positive integers.

1976 ◽  
Vol 28 (6) ◽  
pp. 1251-1268 ◽  
Author(s):  
Peter Tannenbaum

A neofield of order v, Nv( + , •), is an algebraic system of v elements including 0 and 1,0 ≠ 1, with two binary operations + and • such that (Nv, + ) is a loop with identity element 0; (Nv*, •) is a group with identity element 1 (where Nv* = Nv\﹛0﹜) and every element of Nv is both right and left distributive (i.e., (y + z)x = yx + zx and x(y + z) = xy + xz for all y, z∈ Nv).


1961 ◽  
Vol 13 ◽  
pp. 587-592
Author(s):  
Charles W. Curtis

In this paper, A denotes a ring with an identity element 1, and B a subring of A containing 1 such that B satisfies the left and right minimum conditions, and A is a finitely generated left and right B-module. The identity element 1 is required to act as the identity operator on all modules which we shall consider. For any left B-module V, there is a standard construction of a left A -module which is, roughly speaking, the smallest A -module containing V.


1985 ◽  
Vol 28 (1) ◽  
pp. 67-72
Author(s):  
A. D. Sands

By a ring we shall mean an associative ring not necessarily containing an identity element. The fundamental definitions and properties of radicals may be found in Divinsky [2]. Similarly we refer to Howie [3] for the semigroup concepts.If R is a ring Mn(R) will denote the ring of n × n matrices with entries from R. For many important radicals α it has been shown that α(Mn(R)) = Mn(α(R)) for all rings R and all positive integers n. However this is not the case for all radicals α. Associated with each radical α we define a set of positive integers S(α) by


2016 ◽  
Vol 09 (04) ◽  
pp. 1650090 ◽  
Author(s):  
Seda Oğuz ◽  
Eylem G. Karpuz

In [Finite presentability of Bruck–Reilly extensions of groups, J. Algebra 242 (2001) 20–30], Araujo and Ruškuc studied finite generation and finite presentability of Bruck–Reilly extension of a group. In this paper, we aim to generalize some results given in that paper to generalized Bruck–Reilly ∗-extension of a group. In this way, we determine necessary and sufficent conditions for generalized Bruck–Reilly ∗-extension of a group, [Formula: see text], to be finitely generated and finitely presented. Let [Formula: see text] be a group, [Formula: see text] be morphisms and [Formula: see text] ([Formula: see text] and [Formula: see text] are the [Formula: see text]- and [Formula: see text]-classes, respectively, contains the identity element [Formula: see text] of [Formula: see text]). We prove that [Formula: see text] is finitely generated if and only if there exists a finite subset [Formula: see text] such that [Formula: see text] is generated by [Formula: see text]. We also prove that [Formula: see text] is finitely presented if and only if [Formula: see text] is presented by [Formula: see text], where [Formula: see text] is a finite set and [Formula: see text] [Formula: see text] for some finite set of relations [Formula: see text].


2018 ◽  
Vol 1 (October) ◽  
pp. 67-75
Author(s):  
Suesthi Rahayuningsih ◽  
Feriyanto Feriyanto

The purposes of this research are 1) to describe the errors of thinking process of male student in solving group problems; 2) to describe the errors of thinking of female student in solving group problems. This research is an explorative research using a qualitative approach. Data collection is done by task-based interviews. The errors of thinking process based on indicators: fact errors, misconceptions, operating errors and principle errors in solving group problems. The data in this study are the results of interviews and group problem tests. The results of this research show that in fact errors, male subject experienced errors in interpreting the results obtained, whereas female students do not understand the symbols (H, #) and in the context of group symbols. In conceptual errors, the second subject is the same mistake, namely the error in explaining the group and the closed nature. Likewise, with operating errors, there is no significant difference in the second subject. In principle errors, the male subject does not associate the identity element obtained in the previous step in determining the inverse, while the female subject does not associate the set H and binary operations.   Penelitian ini bertujuan  untuk: 1) mendeskripsikan kesalahan proses berpikir mahasiswa laki-laki dalam memecahkan masalah grup; 2) mendeskripsikan kesalahan proses berpikir mahasiswa perempuan dalam memecahkan masalah grup. Penelitian ini merupakan penelitian eksploratif dengan menggunakan pendekatan kualitatif. Pengumpulan data dilakukan dengan wawancara berbasis tugas. Kesalahan proses berpikir berdasarkan indikator: kesalahan fakta, kesalahan konsep, kesalahan operasi dan kesalahan prinsip dalam memecahkan masalah grup.  Data dalam penelitian ini berupa hasil wawancara dan tes masalah grup. Hasil penelitian menunjukkan bahwa pada kesalahan fakta, subjek laki-laki mengalami kesalahan menginterpretasikan hasil yang didapat, sedangkan subjek perempuan tidak memahami simbol (H, #) dan mengalami kesalahan dalam menuliskan simbol grup. Pada kesalahan konsep, kedua subjek mengalami kesalahan yang sama yaitu kesalahan dalam menjelaskan grup dan sifat tertutup.  Demikian juga pada kesalahan operasi, tidak ada perbedaan yang signifikan pada kedua subjek. Pada kesalahan prinsip, subjek laki-laki tidak mengkaitkan elemen identitas yang diperoleh di langkah sebelumnya dalam menentukan invers, sedangkan subjek perempuan tidak mengkaitkan himpunan H dan operasi biner.


2009 ◽  
Vol 19 (06) ◽  
pp. 809-839 ◽  
Author(s):  
JASON BELL ◽  
EMILIE CHARLIER ◽  
AVIEZRI S. FRAENKEL ◽  
MICHEL RIGO

Consider a nonstandard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0,1} without two consecutive 1. Given a set X of integers such that the language of their greedy representations in this system is accepted by a finite automaton, we consider the problem of deciding whether or not X is a finite union of arithmetic progressions. We obtain a decision procedure for this problem, under some hypothesis about the considered numeration system. In a second part, we obtain an analogous decision result for a particular class of abstract numeration systems built on an infinite regular language.


2000 ◽  
Vol 61 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Nadir Trabelsi

LetGbe a finitely generated soluble group. The main result of this note is to prove thatGis nilpotent-by-finite if, and only if, for every pairX,Yof infinite subsets ofG, there exist anxinX,yinYand two positive integersm=m(x,y),n=n(x,y) satisfying [x,nym] = 1. We prove also that ifGis infinite and ifmis a positive integer, thenGis nilpotent-by-(finite of exponent dividingm) if, and only if, for every pairX,Yof infinite subsets ofG, there exist anxinX,yinYand a positive integern=n(x,y) satisfying [x,nym] = 1.


1970 ◽  
Vol 63 (3) ◽  
pp. 244-247
Author(s):  
Margaret Wiscamb

When we teach numeration Systems in bases other than ten, we usually con-fine our discussion 1o the positive integers. The student with an inquiring mind (and I hope you are fortunate enough to have one in every class) may see avenues for further exploration and ask questions such as these: How about decimal fractions—can we change them to some other base? Can we have “decimal” fractions in bases other than ten?


2006 ◽  
Vol 12 (1) ◽  
pp. 55-62
Author(s):  
Angela L.E. Walmsley

Numbers have been recorded in a variety of ways throughout time. For example, the Babylonians used marks pressed in clay; the Egyptians used papyrus and ink brushes to create tally marks; and the Maya introduced a symbol for zero (Billstein, Libeskind, and Lott 2001). All these ancient peoples used numerals, or written symbols, to express what they meant mathematically. They created their own numeration system, which is a collection of uniform symbols and properties to express numbers systematically. The Hindu- Arabic system is one such numeration method; however, understanding others can reveal to students that our current system finds its roots in what has come before.


Author(s):  
Yanhui Wang ◽  
Yuhan Wang ◽  
Xueming Ren ◽  
Kar Ping Shum

Quasi-automatic semigroups are extensions of a Cayley graph of an automatic group. Of course, a quasi-automatic semigroup generalizes an automatic semigroup. We observe that a semigroup [Formula: see text] may be automatic only when [Formula: see text] is finitely generated, while a semigroup may be quasi-automatic but it is not necessary finitely generated. Similar to the usual automatic semigroups, a quasi-automatic semigroup is closed under direct and free products. Furthermore, a semigroup [Formula: see text] is graph automatic if and only if [Formula: see text] with a zero element adjoined is graph automatic, and also a semigroup [Formula: see text] is graph automatic if and only if [Formula: see text] with an identity element adjoined is graph automatic. However, the class of quasi-automatic semigroups is a much wider class than the class of automatic semigroups. In this paper, we show that every automatic semigroup is quasi-automatic but the converse statement is not true (see Example 3.6). In addition, we notice that the quasi-automatic semigroups are invariant under the changing of generators, while a semigroup may be automatic with respect to a finite generating set but not the other. Finally, the connection between the quasi-automaticity of two semigroups [Formula: see text] and [Formula: see text], where [Formula: see text] is a subsemigroup with finite Rees index in [Formula: see text] will be investigated and considered.


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