scholarly journals Dual Number Meadows

2019 ◽  
Author(s):  
Jan Aldert Bergstra
Keyword(s):  
Characteristic Zero ◽  
Equational Theory ◽  
Rational Numbers ◽  
Zero Element ◽  
Open Problems ◽  
Dual Number ◽  
Initial Algebra

The class of dual number meadows is introduced. By definition this class is a quasivariety. Dual number meadows contain a non-zero element the square of which is zero. These structures are non-involutive and coregular. Some properties of the equational theory of dual number meadows are discussed and an initial algebra specification is given for the minimal dual number meadow of characteristic zero which contains the dual rational numbers. Several open problems are stated.

The Group Ring Of a Class Of Infinite Nilpotent Groups

1955 ◽  
Vol 7 ◽  
pp. 169-187 ◽  
Author(s):  
S. A. Jennings
Keyword(s):  
Nilpotent Group ◽  
Group Ring ◽  
Characteristic Zero ◽  
Discrete Group ◽  
Nilpotent Groups ◽  
Zero Element ◽  
Free Nilpotent Group ◽  
Image Position ◽  
Torsion Free ◽  
The Ideal

Introduction. In this paper we study the (discrete) group ring Γ of a finitely generated torsion free nilpotent group over a field of characteristic zero. We show that if Δ is the ideal of Γ spanned by all elements of the form G − 1, where G ∈ , thenand the only element belonging to Δw for all w is the zero element (cf. (4.3) below).

scholarly journals Méthodes fonctionnelles pour la transcendance en caractéristique finie

1994 ◽  
Vol 50 (2) ◽  
pp. 273-286 ◽  
Author(s):  
Laurent Denis
Keyword(s):  
Exponential Function ◽  
Characteristic Zero ◽  
Algebraic Closure ◽  
Algebraic Groups ◽  
Zero Element ◽  
Finite Characteristic ◽  
First Derivative ◽  
Linearly Independent ◽  
Divisibility Properties

There are essentially two ways to obtain transcendence results in finite characteristic. The first, historically, is to use Ore's lemma and to prove that a series whose coefficients satisfy well-behaved divisibility properties cannot be a zero of an additive polynomial. This method is of the same kind as the method of p–automata. The second one is to try to imitate the usual methods in characteristic zero and to do transcendence theory with t–modules analogously to what we can do with algebraic groups. We want to show here that transcendence results over Fq(T) can also be obtained with the help of the variable T. If ec(z) is the Carlitz exponential function and e = ec(1), we obtain, in particular, that 1, e, …, e(p–2) (the P–2 first derivative of e with respect to T) are linearly independent over the algebraic closure of Fq(T). A corollary is that for every non-zero element α in Fq((1/T)), αpe and αec(e1/p) are transcendental over Fq(T). By changing the variable and using older results we also obtain the transcendence of ec(ω) for all ω ∈ Fq((1/T)) such that ω(T) and ω(Ti) are not zero and linearly dependent over Fq (Ti) (q > 2i + 1). Such u appear to be transcendental by the method of Mahler if i is not a power of p.

scholarly journals Spiking Neural P Systems with Weights

2010 ◽  
Vol 22 (10) ◽  
pp. 2615-2646 ◽  
Author(s):  
Jun Wang ◽  
Hendrik Jan Hoogeboom ◽  
Linqiang Pan ◽  
Gheorghe Păun ◽  
Mario J. Pérez-Jiménez
Keyword(s):  
Rational Numbers ◽  
P Systems ◽  
Natural Numbers ◽  
Open Problems ◽  
Spiking Neural P Systems ◽  
Semilinear Sets ◽  
The Family ◽  
Neuron Fire ◽  
Hard Problems

A variant of spiking neural P systems with positive or negative weights on synapses is introduced, where the rules of a neuron fire when the potential of that neuron equals a given value. The involved values—weights, firing thresholds, potential consumed by each rule—can be real (computable) numbers, rational numbers, integers, and natural numbers. The power of the obtained systems is investigated. For instance, it is proved that integers (very restricted: 1, −1 for weights, 1 and 2 for firing thresholds, and as parameters in the rules) suffice for computing all Turing computable sets of numbers in both the generative and the accepting modes. When only natural numbers are used, a characterization of the family of semilinear sets of numbers is obtained. It is shown that spiking neural P systems with weights can efficiently solve computationally hard problems in a nondeterministic way. Some open problems and suggestions for further research are formulated.

scholarly journals The Transrational Numbers as an Abstract Data Type

2020 ◽  
Author(s):  
Jan Aldert Bergstra ◽  
John V. Tucker
Keyword(s):  
Rational Numbers ◽  
Data Type ◽  
Abstract Data Type ◽  
Constant Symbol ◽  
Total Function ◽  
Initial Algebra ◽  
Abstract Data ◽  
Initial Algebra Semantics

In an arithmetical structure one can make division a total function by defining 1/0 to be an element of the structure, or by adding a new element, such as an error element also denoted with a new constant symbol, an unsigned infinity or one or both signed infinities, one positive and one negative. We define an enlargement of a field to a transfield, in which division is totalised by setting 1/0 equal to the positive infinite value and -1/0 equal to its opposite, and which also contains an error element to help control their effects. We construct the transrational numbers as a transfield of the field of rational numbers and consider it as an abstract data type. We give it an equational specification under initial algebra semantics.

On Duo Group Rings

2011 ◽  
Vol 18 (01) ◽  
pp. 163-170
Author(s):  
Weidong Gao ◽  
Yuanlin Li
Keyword(s):  
Group Ring ◽  
Characteristic Zero ◽  
Integral Domain ◽  
Torsion Group ◽  
Rational Numbers ◽  
Group Rings ◽  
Quaternion Group ◽  
Quotient Field ◽  
Ring Of Algebraic Integers ◽  
Field Integral

It is shown that if the group ring RQ8 of the quaternion group Q8 of order 8 over an integral domain R is duo, then R is a field for the following cases: (1) char R ≠ 0, and (2) char R = 0 and S ⊆ R ⊆ KS, where S is a ring of algebraic integers and KS is its quotient field. Hence, we confirm that the field ℚ of rational numbers is the smallest integral domain R of characteristic zero such that RQ8 is duo. A non-field integral domain R of characteristic zero for which RQ8 is duo is also identified. Moreover, we give a description of when the group ring RG of a torsion group G is duo.

scholarly journals Maximal subfields of algebraically closed fields

1980 ◽  
Vol 29 (4) ◽  
pp. 462-468 ◽  
Author(s):  
Robert M. Guralnick ◽  
Michael D. Miller
Keyword(s):  
Galois Group ◽  
Characteristic Zero ◽  
Nonempty Subset ◽  
Rational Numbers ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
Closed Fields ◽  
Algebraically Closed Fields

AbstractLet K be an algebraically closed field of characteristic zero, and S a nonempty subset of K such that S Q = Ø and card S < card K, where Q is the field of rational numbers. By Zorn's Lemma, there exist subfields F of K which are maximal with respect to the property of being disjoint from S. This paper examines such subfields and investigates the Galois group Gal K/F along with the lattice of intermediate subfields.

Some open problems on locally finite or locally nilpotent derivations and ℰ-derivations

2018 ◽  
Vol 20 (04) ◽  
pp. 1750056 ◽  
Author(s):  
Wenhua Zhao
Keyword(s):  
Commutative Ring ◽  
Characteristic Zero ◽  
Associative Algebras ◽  
Open Problems ◽  
Integral Domains ◽  
Locally Finite ◽  
Locally Nilpotent ◽  
Base Ring ◽  
Lf Formula ◽  
Algebra Endomorphism

Let [Formula: see text] be a commutative ring and [Formula: see text] an [Formula: see text]-algebra. An [Formula: see text]-[Formula: see text]-derivation of [Formula: see text] is an [Formula: see text]-linear map of the form [Formula: see text] for some [Formula: see text]-algebra endomorphism [Formula: see text] of [Formula: see text], where [Formula: see text] denotes the identity map of [Formula: see text]. In this paper, we discuss some open problems on whether or not the image of a locally finite (LF) [Formula: see text]-derivation or [Formula: see text]-[Formula: see text]-derivation of [Formula: see text] is a Mathieu subspace [W. Zhao, Generalizations of the image conjecture and the Mathieu conjecture, J. Pure Appl. Algebra 214 (2010) 1200–1216; Mathieu subspaces of associative algebras, J. Algebra 350(2) (2012) 245–272] of [Formula: see text], and whether or not a locally nilpotent (LN) [Formula: see text]-derivation or [Formula: see text]-[Formula: see text]-derivation of [Formula: see text] maps every ideal of [Formula: see text] to a Mathieu subspace of [Formula: see text]. We propose and discuss two conjectures which state that both questions above have positive answers if the base ring [Formula: see text] is a field of characteristic zero. We give some examples to show the necessity of the conditions of the two conjectures, and discuss some positive cases known in the literature. We also show some cases of the two conjectures. In particular, both the conjectures are proved for LF or LN algebraic derivations and [Formula: see text]-[Formula: see text]-derivations of integral domains of characteristic zero.

Arithmetical definability of field elements

1951 ◽  
Vol 16 (2) ◽  
pp. 125-126 ◽  
Author(s):  
Raphael M. Robinson
Keyword(s):  
Characteristic Zero ◽  
Rational Numbers ◽  
Free Variable ◽  
The Other ◽  
Necessary Condition ◽  
Algebraic Numbers ◽  
Real Numbers ◽  
Fourth Root ◽  
Arithmetical Condition ◽  
Image Position

If F is a field, and α is an element of F, we say that α is arithmetically definable in F if there is a formula containing one free variable and any number of bound variables, involving only the concepts of elementary logic and the operations of addition and multiplication, which is satisfied by α and by no other element of F. The range of the bound variables is understood to be F. Without changing the sense of the above definition, we can allow in our formulas symbols for specific integers, or even (if F has characteristic zero) symbols for specific rational numbers, since these are arithmetically definable.As an example, consider the field F = R(2¼), obtained by adjoining the positive fourth root of 2 to the field R of rationals. Notice that 2¼ is not defined arithmetically by the formula x2 = 2, since this equation has two roots in F.However, 2¼ may be defined arithmetically by the equivalencewhere we have used the logical symbols ↔ (if and only if), ∨ (there exists), and ∧ (and). For the equation y4 = 2 is satisfied by no elements of F except y = ±2¼, and in both cases y2 = 2¼. On the other hand, 2¼ is not arithmetically definable in F, since there is an automorphism of F which takes 2¼ into −2¼, so that every arithmetical condition satisfied by 2¼ is also satisfied by −2¼.In any field F, a necessary condition for the arithmetical definability of an element α is that α should be fixed for all automorphisms of F. That this condition is not always sufficient is shown by considering the field of real numbers. Here there is no automorphism but the identity, but there can of course be but a denumerable infinity of arithmetically definable real numbers. Tarski has shown that only the algebraic numbers are arithmetically definable.

Root Extensions and Factorization in Affine Domains

2010 ◽  
Vol 53 (2) ◽  
pp. 247-255 ◽  
Author(s):  
P. Etingof ◽  
P. Malcolmson ◽  
F. Okoh
Keyword(s):  
Characteristic Zero ◽  
Zero Element ◽  
Ring Extension ◽  
Integral Domains ◽  
Root Extension ◽  
Noetherian Domain ◽  
Irreducible Elements ◽  
Finite Set ◽  
Integrally Closed ◽  
Positive Integers

AbstractAn integral domain R is IDPF (Irreducible Divisors of Powers Finite) if, for every non-zero element a in R, the ascending chain of non-associate irreducible divisors in R of an stabilizes on a finite set as n ranges over the positive integers, while R is atomic if every non-zero element that is not a unit is a product of a finite number of irreducible elements (atoms). A ring extension S of R is a root extension or radical extension if for each s in S, there exists a natural number n(s) with sn(s) in R. In this paper it is shown that the ascent and descent of the IDPF property and atomicity for the pair of integral domains (R, S) is governed by the relative sizes of the unit groups U(R) and U(S) and whether S is a root extension of R. The following results are deduced from these considerations: An atomic IDPF domain containing a field of characteristic zero is completely integrally closed. An affine domain over a field of characteristic zero is IDPF if and only if it is completely integrally closed. Let R be a Noetherian domain with integral closure S. Suppose the conductor of S into R is non-zero. Then R is IDPF if and only if S is a root extension of R and U(S)/U(R) is finite.

scholarly journals Rational rigidity for

2014 ◽  
Vol 150 (10) ◽  
pp. 1679-1702 ◽  
Author(s):  
Robert Guralnick ◽  
Gunter Malle
Keyword(s):  
Algebraic Group ◽  
Characteristic Zero ◽  
Reductive Group ◽  
Rational Numbers ◽  
Galois Groups ◽  
Dual Group ◽  
Character Table ◽  
Short List ◽  
Exceptional Groups

AbstractWe prove the existence of certain rationally rigid triples in${E}_{8}(p)$for good primes$p$(i.e. $p>5$) thereby showing that these groups occur as Galois groups over the field of rational numbers. We show that these triples arise from rigid triples in the algebraic group and prove that they generate an interesting subgroup in characteristic zero. As a byproduct of the proof, we derive a remarkable symmetry between the character table of a finite reductive group and that of its dual group. We also give a short list of possible overgroups of regular unipotent elements in simple exceptional groups.

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