scholarly journals The invariant polynomial algebras for the groups ISL(n) and ISp(n)

1984 ◽  
Vol 94 ◽  
pp. 61-73 ◽  
Author(s):  
Hitoshi Kaneta
Keyword(s):  
Linear Group ◽  
Polynomial Algebra ◽  
Invariant Polynomial ◽  
Polynomial Algebras ◽  
Independent Element

This paper is a continuation to the previous one [3], We shall show that, for the inhomogeneous linear group ISL(n + 1, R) (resp. ISp(n, R)), the coadjoint invariant polynomial algebra is generated by one (resp. n) algebraically independent element. We shall state our results more precisely.

scholarly journals The invariant polynomial algebras for the groups IU(n) and ISO(n)

1984 ◽  
Vol 94 ◽  
pp. 43-59 ◽  
Author(s):  
Hitoshi Kaneta
Keyword(s):  
Lie Algebras ◽  
Lie Group ◽  
Dual Space ◽  
Polynomial Algebra ◽  
Invariant Polynomial ◽  
Coadjoint Representation ◽  
Finitely Generated ◽  
Polynomial Algebras ◽  
Enveloping Algebras ◽  
Connected Lie Group

By the coadjoint representation of a connected Lie group G with the Lie algebra g we mean the representation CoAd(g) = tAd(g-1) in the dual space g*. Imitating Chevalley’s argument for complex semi-simple Lie algebras, we shall show that the CoAd (G)-invariant polynomial algebra on g* is finitely generated by algebraically independent polynomials when G is the inhomogeneous linear group IU(n) or ISO(n). In view of a well-known theorem [8, p. 183] our results imply that the centers of the enveloping algebras for the (or the complexified) Lie algebras of these groups are also finitely generated. Recently much more inhomogeneous groups have been studied in a similar context [2]. Our results, however, are further reaching as far as the groups IU(n) and ISO(n) are concerned [cf. 3, 4, 6, 7, 9].

FIXED ELEMENTS OF NONINJECTIVE ENDOMORPHISMS OF POLYNOMIAL ALGEBRAS IN TWO VARIABLES

2016 ◽  
Vol 95 (2) ◽  
pp. 209-213
Author(s):  
YUEYUE LI ◽  
JIE-TAI YU
Keyword(s):  
Associative Algebra ◽  
Characteristic Zero ◽  
Polynomial Algebra ◽  
Free Associative Algebra ◽  
Polynomial Algebras ◽  
Fixed Element ◽  
The Given

Let $A_{2}$ be a free associative algebra or polynomial algebra of rank two over a field of characteristic zero. The main results of this paper are the classification of noninjective endomorphisms of $A_{2}$ and an algorithm to determine whether a given noninjective endomorphism of $A_{2}$ has a nontrivial fixed element for a polynomial algebra. The algorithm for a free associative algebra of rank two is valid whenever an element is given and the subalgebra generated by this element contains the image of the given noninjective endomorphism.

On the hit problem for the unstable $\mathscr A$-module $\mathcal P_5 = H^*((K(\mathbb F_2, 1))^{\times 5}, \mathbb F_2)$ and application

2021 ◽  
Author(s):  
Đặng Võ Phúc
Keyword(s):  
Algebraic Topology ◽  
Homotopy Theory ◽  
Polynomial Algebra ◽  
Steenrod Algebra ◽  
Minimal Set ◽  
Open Problems ◽  
Polynomial Algebras ◽  
Prime Field ◽  
Trivial Element ◽  
Hit Problem

Let us consider the prime field of two elements, $\mathbb F_2.$ One of the open problems in Algebraic topology is the hit problem for a module over the mod 2 Steenrod algebra $\mathscr A$. More specifically, this problem asks a minimal set of generators for the polynomial algebra $\mathcal P_m:=\mathbb F_2[x_1, x_2, \ldots, x_m]$ regarded as a connected unstable $\mathscr A$-module on $m$ variables $x_1, \ldots, x_m,$ each of degree one. The algebra $\mathcal P_m$ is the cohomology with $\mathbb F_2$-coefficients of the product of $m$ copies of the Eilenberg-MacLan space of type $(\mathbb F_2, 1).$ The hit problem has been thoroughly studied for 35 years in a variety of contexts by many authors and completely solved for $m\leq 4.$ Furthermore, it has been closely related to some classical problems in the homotopy theory and applied in studying the $m$-th Singer algebraic transfer $Tr^{\mathscr A}_m$ \cite{W.S1}. This transfer is one of the useful tools for studying the Adams $E^{2}$-term, ${\rm Ext}_{\mathscr A}^{*, *}(\mathbb F_2, \mathbb F_2) = H^{*, *}(\mathscr A, \mathbb F_2).$The aim of this work is to continue our study of the hit problem of five variables. At the same time, this result will be applied to the investigation of the fifth transfer of Singer and the modular representation of the general linear group of rank 5 over $\mathbb F_2.$ More precisely, we grew out of a previous result of us in \cite{D.P3} on the hit problem for $\mathscr A$-module $\mathcal P_5$ in the generic degree $5(2^t-1) + 18.2^t$ with $t$ an arbitrary non-negative integer. The result confirms Sum's conjecture \cite{N.S2} on the relation between the minimal set of $\mathscr A$-generators for the polynomial algebras $\mathcal P_{m-1}$ and $\mathcal P_{m}$ in the case $m=5$ and the above generic degree. Moreover, by using our result \cite{D.P3} and a presentation in the $\lambda$-algebra of $Tr_5^{\mathscr A}$, we show that the non-trivial element $h_1e_0 = h_0f_0\in {\rm Ext}_{\mathscr A}^{5, 5+(5(2^0-1) + 18.2^0)}(\mathbb F_2, \mathbb F_2)$ is in the image of the fifth transfer and that $Tr^{\mathscr A}_5$ is an isomorphism in the bidegree $(5, 5+(5(2^0-1) + 18.2^0)).$ In addition, the behavior of $Tr^{\mathscr A}_5$ in the bidegree $(5, 5+(5(2^t-1) + 18.2^t))$ when $t\geq 1$ was also discussed. This method is different from that of Singer in studying the image of the algebraic transfer.

scholarly journals TRIPLY-GRADED LINK HOMOLOGY AND HOCHSCHILD HOMOLOGY OF SOERGEL BIMODULES

2007 ◽  
Vol 18 (08) ◽  
pp. 869-885 ◽  
Author(s):  
MIKHAIL KHOVANOV
Keyword(s):  
Group Action ◽  
Braid Group ◽  
Polynomial Algebra ◽  
Homology Theory ◽  
Hochschild Homology ◽  
Polynomial Algebras ◽  
Homology Groups ◽  
Link Homology ◽  
Soergel Bimodules ◽  
Braid Group Action

We consider a class of bimodules over polynomial algebras which were originally introduced by Soergel in relation to the Kazhdan–Lusztig theory, and which describe a direct summand of the category of Harish–Chandra modules for sl(n). Rouquier used Soergel bimodules to construct a braid group action on the homotopy category of complexes of modules over a polynomial algebra. We apply Hochschild homology to Rouquier's complexes and produce triply-graded homology groups associated to a braid. These groups turn out to be isomorphic to the groups previously defined by Lev Rozansky and the author, which depend, up to isomorphism and overall shift, only on the closure of the braid. Consequently, our construction produces a homology theory for links.

scholarly journals On the algebraic K-theory of truncated polynomial algebras in several variables

2014 ◽  
Vol 13 (1) ◽  
pp. 57-81 ◽  
Author(s):  
Vigleik Angeltveit ◽  
Teena Gerhardt ◽  
Michael A. Hill ◽  
Ayelet Lindenstrauss
Keyword(s):  
Positive Characteristic ◽  
Polynomial Algebra ◽  
Cyclic Homology ◽  
Perfect Field ◽  
Polynomial Algebras ◽  
Trace Map ◽  
Witt Vectors ◽  
Several Variables ◽  
Topological Cyclic Homology ◽  
Field Of Positive Characteristic

AbstractWe consider the algebraic K-theory of a truncated polynomial algebra in several commuting variables, . This naturally leads to a new generalization of the big Witt vectors. If k is a perfect field of positive characteristic we describe the K-theory computation in terms of a cube of these Witt vectors on ℕn. If the characteristic of k does not divide any of the ai we compute the K-groups explicitly. We also compute the K-groups modulo torsion for k = ℤ.To understand this K-theory spectrum we use the cyclotomic trace map to topological cyclic homology, and write as the iterated homotopy cofiber of an n-cube of spectra, each of which is easier to understand.

scholarly journals On generators of the unstable $\mathscr A$-module $H^{*}((K(\mathbb F_2, 1))^{\times 5})$ in a generic degree and applications

2021 ◽  
Author(s):  
Đặng Võ Phúc
Keyword(s):  
Algebraic Topology ◽  
Polynomial Algebra ◽  
Steenrod Algebra ◽  
Modular Representations ◽  
Minimal Set ◽  
Polynomial Algebras ◽  
Prime Field ◽  
Important Open Problem ◽  
Hit Problem ◽  
The Relationship

Let us consider the prime field of two elements, $\mathbb F_2.$ It is well-known that the classical "hit problem" for a module over the mod 2 Steenrod algebra $\mathscr A$ is an interesting and important open problem of Algebraic topology, which asks a minimal set of generators for the polynomial algebra $\mathcal P_m:=\mathbb F_2[x_1, x_2, \ldots, x_m]$, regarded as a connected unstable $\mathscr A$-module on $m$ variables $x_1, \ldots, x_m,$ each of degree 1. The algebra $\mathcal P_m$ is the $\mathbb F_2$-cohomology of the product of $m$ copies of the Eilenberg-MacLan complex $K(\mathbb F_2, 1).$ Although the hit problem has been thoroughly studied for more than 3 decades, solving it remains a mystery for $m\geq 5.$ The aim of this work is of studying the hit problem of five variables. More precisely, we develop our previous work \cite{D.P3} on the hit problem for $\mathscr A$-module $\mathcal P_5$ in a degree of the generic form $n_t:=5(2^t-1) + 18.2^t,$ for any non-negative integer $t.$ An efficient approach to solve this problem had been presented. Moreover, we provide an algorithm in MAGMA for verifying the results and studying the hit problem in general. As an consequence, the calculations confirmed Sum's conjecture \cite{N.S2} for the relationship between the minimal sets of $\mathscr A$-generators of the polynomial algebras $\mathcal P_{m-1}$ and $\mathcal P_{m}$ in the case $m=5$ and degree $n_t.$ Two applications of this study are to determine the dimension of $\mathcal P_6$ in the generic degree $5(2^{t+4}-1) + n_1.2^{t+4}$ for all $t > 0$ and describe the modular representations of the general linear group of rank 5 over $\mathbb F_2.$ As a corollary, the cohomological "transfer", defined by W. Singer \cite{W.S1}, is an isomorphism at the bidegree $(5, 5+n_0).$ Singer's transfer is one of the relatively efficient tools to approach the structure of mod-2 cohomology of the Steenrod algebra.

HOCHSCHILD COHOMOLOGY OF POLYNOMIAL ALGEBRAS

2001 ◽  
Vol 03 (03) ◽  
pp. 393-402 ◽  
Author(s):  
MICHAEL PENKAVA ◽  
POL VANHAECKE
Keyword(s):  
Deformation Theory ◽  
Hochschild Cohomology ◽  
Differential Operators ◽  
Polynomial Algebra ◽  
Cohomology Groups ◽  
Polynomial Algebras ◽  
Arbitrary Polynomial

In this paper we investigate the Hochschild cohomology groups H2(A) and H3(A) for an arbitrary polynomial algebra A. We also show that the corresponding cohomology groups which are built from differential operators inject in H2(A) and H3(A) and we give an application to deformation theory.

scholarly journals On the dimension of $H^{*}((\mathbb Z_2)^{\times t}, \mathbb Z_2)$ as a module over Steenrod ring

2021 ◽  
Author(s):  
Đặng Võ Phúc
Keyword(s):  
Tensor Product ◽  
Finite Field ◽  
Linear Group ◽  
General Linear Group ◽  
Polynomial Algebra ◽  
General Linear ◽  
Minimal Set ◽  
Equivalent Problem ◽  
Monomial Basis ◽  
Trivial Subgroup

We write $\mathbb P$ for the polynomial algebra in one variable over the finite field $\mathbb Z_2$ and $\mathbb P^{\otimes t} = \mathbb Z_2[x_1, \ldots, x_t]$ for its $t$-fold tensor product with itself. We grade $\mathbb P^{\otimes t}$ by assigning degree $1$ to each generator. We are interested in determining a minimal set of generators for the ring of invariants $(\mathbb P^{\otimes t})^{G_t}$ as a module over Steenrod ring, $\mathscr A_2.$ Here $G_t$ is a subgroup of the general linear group $GL(t, \mathbb Z_2).$ An equivalent problem is to find a monomial basis of the space of "unhit" elements, $\mathbb Z_2\otimes_{\mathscr A_2} (\mathbb P^{\otimes t})^{G_t}$ in each $t$ and degree $n\geq 0.$ The structure of this tensor product is proved surprisingly difficult and has been not yet known for $t\geq 5,$ even for the trivial subgroup $G_t = \{e\}.$ In the present paper, we consider the subgroup $G_t = \{e\}$ for $t \in \{5, 6\},$ and obtain some new results on $\mathscr A_2$-generators of $(\mathbb P^{\otimes t})^{G_t}$ in some degrees. At the same time, some of their applications have been proposed. We also provide an algorithm in MAGMA for verifying the results. This study can be understood as a continuation of our recent works in [23, 25].

scholarly journals On the dimension of $H^{*}((\mathbb Z_2)^{\times t}, \mathbb Z_2)$ as a module over Steenrod ring

2021 ◽  
Author(s):  
Đặng Võ Phúc
Keyword(s):  
Positive Integer ◽  
Tensor Product ◽  
Finite Field ◽  
Vector Space ◽  
Linear Group ◽  
Computer Algebra ◽  
General Linear Group ◽  
Polynomial Algebra ◽  
Minimal Set ◽  
Trivial Subgroup

We write $\mathbb P$ for the polynomial algebra in one variable over the finite field $\mathbb Z_2$ and $\mathbb P^{\otimes t} = \mathbb Z_2[x_1, \ldots, x_t]$ for its $t$-fold tensor product with itself. We grade $\mathbb P^{\otimes t}$ by assigning degree $1$ to each generator. We are interested in determining a minimal set of generators for the ring of invariants $(\mathbb P^{\otimes t})^{G_t}$ as a module over Steenrod ring, $\mathscr A_2.$ Here $G_t$ is a subgroup of the general linear group $GL(t, \mathbb Z_2).$ Equivalently, we want to find a basis of the $\mathbb Z_2$-vector space $\mathbb Z_2\otimes_{\mathscr A_2} (\mathbb P^{\otimes t})^{G_t}$ in each degree $n\geq 0.$ The problem is proved surprisingly difficult and has been not yet known for $t\geq 5.$ In the present paper, we consider the trivial subgroup $G_t = \{e\}$ for $t \in \{5, 6\},$ and obtain some new results on $\mathscr A_2$-generators for $(\mathbb P^{\otimes 5})^{G_5}$ in degree $5(2^{1} - 1) + 13.2^{1}$ and for $(\mathbb P^{\otimes 6})^{G_6}$ in "generic" degree $n = 5(2^{d+4}-1) + 47.2^{d+4}$ with a positive integer $d.$ An efficient approach to studying $(\mathbb P^{\otimes 5})^{G_5}$ in this case has been provided. In addition, we introduce an algorithm on the MAGMA computer algebra for the calculation of this space. This study is a continuation of our recent works in \cite{D.P2, D.P4}.

scholarly journals NAKAYAMA AUTOMORPHISMS OF ORE EXTENSIONS OVER POLYNOMIAL ALGEBRAS

2019 ◽  
Vol 62 (3) ◽  
pp. 518-530 ◽  
Author(s):  
LIYU LIU ◽  
WEN MA
Keyword(s):  
Algebraic Geometry ◽  
Cyclic Group ◽  
Invariant Theory ◽  
Polynomial Algebra ◽  
Ore Extension ◽  
Polynomial Algebras ◽  
Noncommutative Algebraic Geometry ◽  
Ore Extensions ◽  
Group Sharing ◽  
Noncommutative Invariant Theory

AbstractNakayama automorphisms play an important role in the fields of noncommutative algebraic geometry and noncommutative invariant theory. However, their computations are not easy in general. We compute the Nakayama automorphism ν of an Ore extension R[x; σ, δ] over a polynomial algebra R in n variables for an arbitrary n. The formula of ν is obtained explicitly. When σ is not the identity map, the invariant EG is also investigated in terms of Zhang’s twist, where G is a cyclic group sharing the same order with σ.

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