Алгебры бинарных формул для слабо циклически минимальных теорий: монотонный влево случай

Introduction: Development of practical post-quantum signature algorithms is a current challenge in the area of cryptography. Recently, several candidates on post-quantum signature schemes, in which the exponentiation operations in a hidden commutative group contained in a non-commutative algebra is used, were proposed. Search for new mechanisms of using a hidden group, while developing signature schemes resistant to quantum attacks, is of significant practical interest. Purpose: Development of a new method for designing post-quantum signature algorithms on finite non-commutative associative algebras. Results: A novel method for developing digital signature algorithms on non-commutative algebras. A new four-dimensional finite non-commutative associative algebra set over the ground field GF(p) have been proposed as algebraic support of the signature algorithms. To provide a higher performance of the algorithm, in the introduced algebra the vector multiplication is defined by a sparse basis vector multiplication table. Study of the algebra structure has shown that it can be represented as a set of commutative subalgebras of three different types, which intersect exactly in the set of scalar vectors. Using the proposed method and introduced algebra, a new post-quantum signature scheme has been designed. The introduced method is characterized in using one of the elements of the signature (e, S) in form of the four-dimensional vector S that is computed as a masked product of two exponentiated elements G and H of a hidden commutative group: S = B-1GnHmC-1, where non-permutable vectors B and C are masking multipliers; the natural numbers n and m are calculated depending on the signed document M and public key. The pair <G, H> composes a minimum generator systems of the hidden group. The signature verification equation has the form R = (Y1SZ1)e(Y2SZ2)e2, where pairwise non-permutable vectors Y1, Z1, Y2, and Z2 are element of the public key and natural number e that is computed depending on the value M and the vector R. Practical relevance: Due to sufficiently small size of public key and signature and high, the developed digital signature scheme represents interest as a practical post-quantum signature algorithm. The introduced method is very attractive to develop a post-quantum digital signature standard.

Post-quantum signature algorithms on noncommutative algebras, using difficulty of solving systems of quadratic equations

David Rees completed his Cambridge undergraduate studies in mathematics in summer 1939; in his first three months of postgraduate work in autumn 1939, he produced a characterization of completely 0-simple semigroups. War then intervened: he worked until the end of the war at Bletchley Park, the British codebreaking centre in Buckinghamshire, where he was part of a team that broke the Enigma code regularly for some critical months during 1940. After the war, he first worked at Manchester University, but moved to Cambridge University in 1948. In the immediate post-war period, he continued with research into semigroups and non-commutative algebra. His first paper was very influential, and he is considered by semigroup theorists to be one of the founding fathers of their subject. At Cambridge, after attending a seminar by Douglas Northcott, Rees changed the focus of his research to commutative Noetherian rings. During an extraordinarily productive period between 1954 and 1961, he produced a string of far-reaching, foundational and deep ideas and results of lasting significance. Highlights include reductions of ideals, his Valuation Theorem, the theory of grade, the graded rings that are nowadays known as ‘Rees rings’, the Artin–Rees Lemma and his characterization of local rings whose completions have zero nilradical. Rees was appointed to the Chair of Pure Mathematics at the University of Exeter in 1958 and elected FRS in 1968. He was awarded the Polya Prize of the London Mathematical Society, and an Honorary DSc by the University of Exeter, in 1993. David Rees was born and brought up in Abergavenny; he was the fourth of five children of Gertrude (née Powell) and (another) David Rees, a corn merchant. The family lived above David's father's corn shop. There is history of both longevity and mathematical ability in David Rees's father's line: his father died at the age of 88, three of his siblings had 90th birthdays and one of his great-great-grandfathers was the Reverend Thomas Rees (1774–1858), a well-known non-conformist minister, who, according to one obituarist, was considered to be the best mathematician in Wales in 1802. David Rees was educated at King Henry VIII Grammar School in Abergavenny. At the time, the school had an excellent headmaster, Wyndham Newcombe, who was also a very good teacher of mathematics. Rees's early teenage years were affected by ill health, and he was absent from school for several terms. During those periods of illness, he studied at home independently, and his mother, armed with lists from the young David, became one of the best customers of the Abergavenny public library. This diligence stood him in good stead when he was able to return to normal schooling: under the guidance of mathematics master L. F. Porter, he was able to catch up quickly with his mathematics. He did rather well in School Certificate examinations in 1934 and 1936, and was awarded a State Scholarship and admission to Sidney Sussex College, Cambridge, where his studies were supervised by Gordon Welchman. Rees started as a Commoner, but was made an Exhibitioner after one year and, after he had come top in the Preliminary Examination for Part II at the end of his second year, he was made a Scholar. Rees was persuaded to take Parts IIB and III together in 1939, and another candidate, Hermann Bondi, with whom he had a friendly rivalry and who only had to take Part IIB at that time, managed to just beat him into second place. Rees began postgraduate work in September 1939, without a proper supervisor, but inspired by ‘wonderful lectures’ by Philip Hall. In the autumn of 1939, he had a rather successful three months, during which he produced a characterization of completely 0-simple semigroups. Here are the relevant definitions. Let S be a semigroup, with operation written multiplicatively. A (two-sided) ideal of S is a non-empty subset A of S such that a s ∈ A and s a ∈ A for all a ∈ A and s ∈ S . A zero element of S is a (necessarily uniquely determined) element 0 ∈ S such that 0 s = 0 = s 0 for all s ∈ S . The semigroup S with zero is called 0-simple if { 0 } and S are its only ideals and there exist s , t ∈ S such that s t ≠ 0 . The semigroup S is said to be completely 0-simple if it is 0-simple and has a non-zero idempotent element e such that the only idempotent f ∈ S for which e f = f e = f ≠ 0 is e itself. Paper [1] was submitted in early May 1940, and represents a very successful start by Rees to postgraduate research. Given Rees's intensive work at Bletchley Park from December 1939 (see §3), most of the work for [1] must have been completed in Rees's first three months of research. In that paper, Rees does thank ‘Mr. P. Hall, both for his encouragement, while this paper was being written, and his very considerable assistance in preparing the paper for publication’. It should be noted that paper [1] is explicitly mentioned in the citation that accompanied David Rees's election as FRS. The phrases ‘Rees matrix semigroup’ and ‘Rees Theorem’ ensure that his name will live on among the semigroup community. By summer 1939, Gordon Welchman had been appointed to work at Bletchley Park, the British codebreaking centre in Buckinghamshire. In December 1939, Welchman knocked on the door of Rees's college rooms to tell him that he had a job for him to do. Rees naturally wanted to know details, but Welchman refused to elaborate, and only after prompting did he tell Rees to meet him a few days later at Bletchley railway station. Rees did so, and in this way was recruited to a team of codebreakers in Hut 6 at Bletchley Park. Welchman recruited several other young mathematicians he knew from Cambridge, including some he had taught at Sidney Sussex College. Even in later life after the veil of secrecy that covered the war-time exploits of Bletchley Park had been lifted, David Rees did not like to talk about his time there. However, it is now clear that he was part of a team that broke the Enigma code regularly for some critical months during the summer and autumn of 1940. The German operators of the Enigma machines were told which three of the five available rotors and which settings to use each day, but they had to choose the initial positions of the rotors and indicate their choices by means of the first three letters of their initial messages. John Herivel, who had also been recruited to Bletchley Park from Sidney Sussex College by Welchman, predicted in February 1940 that some German operators, when tired or stressed, might use short cuts that could be exploited by the Bletchley Park codebreakers. For three months, this lateral thinking by Herivel produced no result; but in May 1940 some of the German operators began to make the predicted mistakes, and David Rees and his fellow codebreakers were able to use the technique known as the ‘Herivel tip’ to break Enigma ciphers for some critical months from May 1940. Herivel has written an account 〈7〉 of the Herivel tip and related matters, in which he attributes the first successful use of the tip to David Rees: see 〈7, pp. 118–119〉. Interestingly, the same book contains a reproduction of a statement by David Rees about the Herivel tip in which he declared that he did not recollect being the person responsible for the first successful use of it, although he conceded that ‘it is possible that my memory is at fault’; see 〈7, p. 122〉. What is not in doubt is that the first successful use of the Herivel tip resulted in much rejoicing, shouting and standing on chairs. Rees thought very highly of Herivel's idea: he described it as ‘brilliant’ in the above-mentioned statement 〈7, p. 122〉; and he is quoted in 〈7, p. 11〉 as having said, in 2000, that ‘of course, the Herivel tip was one of the seminal discoveries of the Second World War’. Rees told the present author in 2007 that, in his opinion, Herivel did not receive the recognition that he deserved. In late 1941, David Rees was seconded to the Enigma Research Section at Bletchley Park, run by Dillwyn (‘Dilly’) Knox, and where the Abwehr Enigma used by the German Secret Service was broken. The so-called ‘Double Cross Committee’ used captured German agents to persuade Hitler that the D-Day landings would be south of Calais rather than in Normandy. It is said that, without the break into the Abwehr Enigma, British intelligence officers could not have known that the deception was working. David Rees subsequently moved to the ‘Newmanry’, the department at Bletchley Park led, for the second half of the war, by M. H. (Max) Newman, for which the first Colossus computer was constructed to assist with codebreaking. The list of subsequently famous mathematicians whom David Rees encountered during his service at Bletchley Park includes A. O. L. Atkin, I. J (Jack) Good, J. A. (Sandy) Green (who worked at Bletchley Park as a teenager), Peter Hilton, Max Newman, G. B. Preston and Shaun Wylie. Sandy Green and Peter Hilton were later to become coauthors of mathematical papers with David Rees, and Rees's third paper [3] (written after the war) was about a paper by Jack Good. There are now available in print numerous articles detailing aspects of the war-time exploits at Bletchley Park; two recent ones are The Guardian's obituary of Peter Hilton 〈23〉 and the Royal Society's Biographical Memoir about William Tutte 〈31〉. Following the end of the war, David Rees resumed his academic studies, and soon found himself working under Max Newman in a different context: he was appointed in 1945 to an Assistant Lectureship in the Department of Mathematics at Manchester University, and Newman was the head of that department. Rees remained at Manchester until 1948, when he was appointed to a University Lectureship at Cambridge; in 1949 he was appointed to a Fellowship at Downing College. He worked in semigroup theory and non-commutative algebra while at Manchester, and continued with these themes for his first years as a Cambridge don. He was very pleased with his joint paper [8] (with Sandy Green) from this time; in it they considered, for positive integers n and r with r ⩾ 2 , the semigroup S n , r (again written multiplicatively) generated by n elements in which each element x satisfies x r = x , but which is otherwise free, and they showed that the question as to whether S n , r is finite is intimately related to Burnside's Conjecture in group theory. Recall that the latter conjecture for r is the statement that, for all n > 0 , the group B n r generated by n elements in which each element x satisfies x r = e , but which is otherwise free, is finite. A striking result from the Green–Rees paper [8] is that the Burnside conjecture for r is true if and only if S n , r + 1 is finite for all n > 0 . David Rees wrote just five papers on semigroup theory, but their influence on the development of that subject has been very substantial. Interested readers might like to consult the tribute 〈11〉 to Rees in Semigroup Forum, where he is described as ‘one of the pioneers of semigroup theory’, as ‘one of the subject's founding fathers’, and as having ‘laid the foundations for a number of important avenues of future research’. However, as David Rees published about forty papers in commutative algebra, it is appropriate that the majority of this obituary be devoted to his contributions to that field. Another addition to the Mathematics faculty at Cambridge in 1948 was Douglas G. Northcott, who had spent 21 post-war months in Princeton, where he had been greatly stimulated by a seminar with the title ‘Valuation theory’ run by Emil Artin and Claude Chevalley, and by much informal guidance from Artin. Northcott returned to Cambridge having become a dedicated algebraist (his PhD work concerned a theory of integration for functions with values in a Banach space). In Princeton, Northcott had, at Artin's suggestion, studied the famous paper 〈28〉 by Weil, and, as a consequence, began to work in the algebra underlying what some refer to as the ‘pre-Grothendieck’ era of algebraic geometry. Thus Northcott became a commutative algebraist. Back in Cambridge, Northcott organized a very successful working seminar on Weil's book 〈29〉. David Rees was a member of the audience, and he was so inspired by the seminar that he too became a commutative algebraist. (Another aspect of Northcott's seminar that was life-changing for Rees was the presence in the audience of Joan Cushen: David and Joan were married in 1952.) David Rees's transition from semigroup theory was gradual and his first paper in commutative algebra ([9], written jointly with Northcott) only appeared in 1954. That paper is central to the next section. Paper [9], written jointly with Douglas Northcott, is, by a long way, David Rees's most-cited research paper: Mathematical Reviews records more than 200 citations of it. It introduced the notion of reductions of ideals. This concept and the related concept of integral closure have had a major influence on research in commutative algebra in the more than 60 years since they were introduced; indeed, even in the present century, hardly a top-level international conference in commutative algebra passes without there being several mentions of reductions. Let b and a be proper ideals of R. The ideal b is said to be a reduction of a if b ⊆ a and there exists s ∈ N 0 (the set of non-negative integers) such that b a s = a s + 1 . One can view such a b as an approximation to a that nevertheless retains some of the properties of a: for example, a prime ideal p of R is a minimal prime ideal of b if and only if it is a minimal prime ideal of a, and when that is the case, the multiplicity of b corresponding to p is equal to the multiplicity of a corresponding to p. (The multiplicity of a corresponding to its minimal prime ideal p is the multiplicity e ( a R p of the ideal a R p of the R p The for the of reduction to David Rees while he was thinking about so-called ideals in a graded S = n ∈ N 0 S n that is as an algebra S 0 , by elements of S + = n ∈ N S n N the set of positive A = n ∈ N A n be a graded ideal of R generated by elements of Rees noted that A n = S n for all n is, A is if and only if there exists ∈ N 0 such that A ( S + = ( S + + 1 . This to the of the concept of The between reductions and integral can be as Let b ⊆ a be ideals of R. b is a reduction of a if and only if each element of a is on the set J of all ideals of R that have b as a reduction has a b b is the of the of and this ideal b is the set of all elements of R that are on The ideal b is called the integral closure of it has the that the ideals of R that have b as a reduction are those between b and b . that b is if b = b . The ideal b is said to be a minimal reduction of a if b is a reduction of a and there is no reduction of a with b (the of is written under the that R is a local with and so that will be in until also will the ideal of Rees and Northcott the ( a of this to be equal to the of ( a ( a , where ( a the graded ∈ N 0 a a + 1 of that reduction of a at ( a that a reduction of a is a minimal reduction of a if and only if it can be generated by ( a and that each reduction of a contains a minimal reduction of Thus all minimal of all minimal reductions of a have ( a on to that ( a can be as 1 , , t ∈ a are said to be in a ∈ N and f ∈ R 1 , , t (the of R in t is a of such that f ( 1 , , t ∈ a , then all the of f in if b is a reduction of a, ( b b = t and { 1 , , t } is a minimal set for it that b is a minimal reduction of a if and only if 1 , , t are in ( a is equal to the number of elements of a that are in a, and a ( a ( a a . mentioned the in the of the of reduction and integral closure in the 60 years since Rees and Northcott published are very and related have been studied in The can some of the influence that these ideas of Rees and Northcott have had, and to in commutative algebra by the book by and on integral That book is dedicated to and David a of and about of Rees's contributions to commutative algebra. In this in which to of the commutative Noetherian some graded rings used by Rees to good these rings are to as ‘Rees and Rees A between graded rings is an that There is an between R a and R ( a . that the graded R ( a a R ( a is to the graded ( a = ∈ N 0 a a + 1 of The R ( a is also called the up of this has its in the that the of R ( a is the underlying the by up ( R with to The of R a , 1 is and Rees used to very good the that, for an ∈ N 0 , the of the graded ideal R a , 1 of R a , 1 is just a . In other R a , 1 R = a . By means of this Rees was able to some about of an ideal in a Noetherian to the where the ideal is and generated by a In that case, are The of Theorem, on the in Rees his use of the above that R is r ∈ = 1 a , then there exists a ∈ a such that r = a r . first with the where a is the ideal R generated by a r ∈ = 1 a , for each ∈ N , r = s for some s ∈ R . s = s + 1 for all ∈ N , since is a in R. R s 1 ⊆ R s 2 ⊆ ⊆ R s ⊆ , and so there exists ∈ N such that R s = R s + 1 . Thus s + 1 = s b for some b ∈ R , from which see that s = s + 1 = s ( b , with b ∈ R . r = s = ( b s = ( b r . In the case, the Rees S = R a , 1 , and set = 1 , a of that Let r ∈ = 1 a . r ∈ = 1 S , and, by the first of this can r = f r for some f ∈ S . f = = b , where b ∈ a for all = , , . of 0 to see that r = b 1 r , and that b 1 ∈ a . In the same paper Rees also a of what is now known as Artin–Rees That also the Rees Lemma (The Artin–Rees Lemma Lemma that R is Let a , b be two ideals of R. there exists ∈ N such that a n b = a n ( a b for all n ⩾ . S = R a , 1 , the Rees of a, and B = b R , 1 S , an ideal of Thus an element = r of R , 1 to B if and only if r ∈ a b for all = , , . B is a graded ideal of the Noetherian and so has a finite set of { b 1 1 , , b } where b ∈ a b for all = 1 , , . Let = { 1 , , } . a n b = a n ( a b for all n ⩾ . (The might it to that ( a b a n ⊆ ( a + 1 b a n ( + 1 for integers n , with 0 n David Rees the name of the as David had his of the in but he did not it for until May paper appeared in in the very in which Emil Artin at a conference in about his of the same and result; M. was to as to who should receive the and that ‘it is the Artin–Rees There is a of the for which that if N is a of a generated then there exists ∈ N such that a n N = a n ( a N for all n ⩾ . This result means that the on N by the on is the on The might like to consult well as being well to the of of a ideal a of the Rees R a , 1 can be used to the integral of the of a, it that R a , 1 R = a for each ∈ N 0 = 1 However, Rees's Valuation Theorem, which is the subject of the next also about the integral of of In a of papers published during an productive period from to David Rees what he called his ‘Valuation which can be as the integral of the of an ideal a of R in of uniquely rings are nowadays to as Rees rings’, while the are called Rees related to the Rees is the as a be a proper ideal of the R. The of a is the a R N 0 { } for which Lemma and Lemma the of for each r ∈ R , the The name is in recognition of P. of the of the theory of ideals in work had a influence on The of the and the of integral closure can be in to the where the underlying A is not and the of Lemma see for a ∈ N 0 , an ideal of A and a , a ∈ A , one can that, if a ∈ , then ( a ⩾ , while if ( a > , then a ∈ . For the statement of Rees's Valuation Theorem, the concept of of including in the where R is not a For properties of and the the is to a of the of the R R p for some minimal prime ideal p of R and a of the of R p that is non-negative on R p . the values of and in { } that, for an r ∈ R , have ( r = if and only if r ∈ p . Valuation that R is Let a be a proper ideal of R. there exist 1 , , of R the of and positive integers e 1 , , e , such that the Rees come in an that their are that, in a ideal is and the Theorem, the statement of which the concept of is an integral such that for each prime ideal p of of the p is a = p ∈ ( , p = 1 p each non-zero a ∈ to only of the prime ideals of of (The that R is that R is an integral its integral closure R is a This result is to in the where R is local and to M. in the that R not be In the about the can be used to Rees's Valuation Theorem, will be on the where R is a in that it is to see where the Rees come A in the of the Valuation from a Noetherian to a commutative Noetherian R is the that, for an ideal a of R and r ∈ R , have r ∈ a if and only if r + p ∈ a + p p for each minimal prime ideal p of R. a of Lemma is related to the integral of of have noted in the that if r ∈ a for a ∈ N , then a ( r ⩾ the Valuation can be used to the statement in Noetherian R. for ∈ N and r ∈ R , it is the that r ∈ a if and only if a ( r ⩾ . This of the Valuation is in such as to about whether two ideals a , b of R are that is, such that a s = b t for some s , t ∈ N . Rees thought that was his best paper, but another of which he was and in which also was In that, he a that had been by in and was related to The latter can be as if S the of in n a and if is a of the of of S that contains must the S be generated In the if is a generated of a and S is a generated integral whose of contains must the S be generated himself in that if the of is 1 or then S is generated In Rees constructed an that showed that the to is For he used and very an Rees the of a of the ideal a on was by in The concept of grade, to the theory of is also to David 1 , , t in R are said to a if they a proper ideal and ( ( 1 , , 1 = ( 1 , , 1 for all = 1 , t . (The of this when = 1 is as ( 0 1 = 0 , that is, 1 is a on In Rees that, for a proper ideal a of each in a has equal to the such that R ( R a , R ≠ 0 . all in a have the same and Rees this to be the of His him to quickly that

This is the last in a series of articles where we are concerned with normal elements of noncommutative Iwasawa algebras over SL n ⁢ ( ℤ p ) {\mathrm{SL}_{n}(\mathbb{Z}_{p})} . Our goal in this portion is to give a positive answer to an open question in [D. Han and F. Wei, Normal elements of noncommutative Iwasawa algebras over SL 3 ⁢ ( ℤ p ) \mathrm{SL}_{3}(\mathbb{Z}_{p}) , Forum Math. 31 2019, 1, 111–147] and make up for an earlier mistake in [F. Wei and D. Bian, Normal elements of completed group algebras over SL n ⁢ ( ℤ p ) \mathrm{SL}_{n}(\mathbb{Z}_{p}) , Internat. J. Algebra Comput. 20 2010, 8, 1021–1039] simultaneously. Let n ( n ≥ 2 {n\geq 2} ) be a positive integer. Let p ( p > 2 {p>2} ) be a prime integer, ℤ p {\mathbb{Z}_{p}} the ring of p-adic integers and 𝔽 p {\mathbb{F}_{p}} the finite filed of p elements. Let G = Γ 1 ⁢ ( SL n ⁢ ( ℤ p ) ) {G=\Gamma_{1}(\mathrm{SL}_{n}(\mathbb{Z}_{p}))} be the first congruence subgroup of the special linear group SL n ⁢ ( ℤ p ) {\mathrm{SL}_{n}(\mathbb{Z}_{p})} and Ω G {\Omega_{G}} the mod-p Iwasawa algebra of G defined over 𝔽 p {\mathbb{F}_{p}} . By a purely computational approach, for each nonzero element W ∈ Ω G {W\in\Omega_{G}} , we prove that W is a normal element if and only if W contains constant terms. In this case, W is a unit. Also, the main result has been already proved under “nice prime” condition by Ardakov, Wei and Zhang [Non-existence of reflexive ideals in Iwasawa algebras of Chevalley type, J. Algebra 320 2008, 1, 259–275; Reflexive ideals in Iwasawa algebras, Adv. Math. 218 2008, 3, 865–901]. This paper currently provides a new proof without the “nice prime” condition. As a consequence of the above-mentioned main result, we observe that the center of Ω G {\Omega_{G}} is trivial.

This article concerns the notion of weak circular minimality being a variant of o-minimality for circularly ordered structures. Algebras of binary isolating formulas are studied for countably categorical weakly circularly minimal theories of convexity rank greater than 1 having both a 1-transitive non-primitive automorphism group and a non-trivial strictly monotonic function acting on the universe of a structure. On the basis of the study, the authors present a description of these algebras. It is shown that there exist both commutative and non-commutative algebras among these ones. A strict m-deterministicity of such algebras for some natural number m is also established.

In this paper we develop techniques that eliminate the need of the Generalized Riemann Hypothesis (GRH) from various (almost all) known results about deterministic polynomial factoring over finite fields. Our main result shows that given a polynomial f(x) of degree n over a finite field k, we can find in deterministic poly(n log n , log|k|) time either a nontrivial factor of f(x) or a nontrivial automorphism of k[x]/(f(x)) of order n. This main tool leads to various new GRH-free results, most striking of which are: 1. Given a noncommutative algebra A of dimension n over a finite field k. There is a deterministic poly(n logn , log|k|) time algorithm to find a zero divisor in A. This is the best known deterministic GRH-free result since R´ (1990) first studied the problem of finding zero divisors in finite algebras and showed that this problem has the same complexity as factoring polynomials over finite fields. 2. Given a positive integer r > 4 such that either 4|r or r has two distinct prime factors. There is a deterministic polynomial time algorithm to find a nontrivial factor of ther-th cyclotomic polynomial over a finite field. This is the best known deterministic GRH-free result since Evdokimov (1989) showed that cyclotomic polynomials can be factored over finite fields in deterministic polynomial time assuming GRH. In this paper, following the seminal work of Lenstra (1991) on constructing isomorphisms between finite fields, we further generalize classical Galois theory constructs

Behaviour of the Frobenius map in a noncommutative world

Purpose of work is the development of post-quantum digital signature algorithms with comparatively small sizes of the public and secret keys and the signature. Research method is the use of a new concept for constructing signature algorithms on finite non-commutative associative algebras, which is distinguished by the multiple occurrences of the signature S in the power verification equation. A public key is generated in the form of a set of vectors every of which is calculated as the product of triples of secret vectors. With a special choice of these triples, it is possible to calculate a signature that satisfies the verification equation. Results of the study are two developed algebraic post-quantum digital signature algorithms of a new type, security of which is based on the computational difficulty of solving systems of many quadratic equations with many unknowns. The difference from the public-key algorithms of multivariate cryptography is that the system of quadratic equations is derived from the formulas for generating the public-key elements in the form of a set of vectors of m-dimensional finite non-commutative algebra with an associative vector multiplication operation. The said formulas define the system of n quadratic vector equations, which reduces to the system of mn quadratic equations over a finite field. Thanks to the “natural” mechanism for the occurrence of the specified system, it is set above the field, the order of which has a large size (97 and 129 bits). The used procedures for generating the public key and signature include the exponentiation operations to the degree of a large size (96 and 128 bits), which are performed over the elements of the secret (hidden) commutative group contained in the algebra. The signature is formed in the form of two elements: a randomizing natural number e and a “fitting” vector S. The signature authentication equation includes a multiple occurrence of the S element and every entry of the vector S is associated with the formation of a product that is exponentiated to a degree dependent on the value of the e element. A significant reduction in the size of public and secret keys and signatures has been achieved, as well as an increase in performance compared to foreign analogues, considered currently as basic algorithms for the adoption of post-quantum digital signature standards.

In present paper we define a new kind of quantized enveloping algebra of (2). We denote this algebra by Ur,t, where r, t are two non-negative integers. It is a non-commutative and non-cocommutative Hopf algebra. If r = 0, then the algebra Ur,t is isomorphic to a tensor product of the algebra of infinite cyclic group and the usual quantum enveloping algebra of (2) as Hopf algebras. The representation of this algebra is studied.

On Hilbert series for commutative and noncommutative graded algebras

In this paper, we develop a theory of free holomorphic functions on noncommutative Reinhardt domains , generated by positive regular free holomorphic functions f in n noncommuting variables and by positive integers m ≥ 1, where is the algebra of all bounded linear operators on a Hilbert space . Noncommutative Berezin transforms are used to study Hardy algebras H ∞ (D f, rad m ) and domain algebras A(D f, rad m ) associated with and compositions of free holomorphic functions. We obtain noncommutative Cartan type results for formal power series, in several noncommuting indeterminates, which leave invariant the nilpotent parts of the corresponding domains. As a consequence, we characterize the set of all free biholomorphic functions with F(0) = 0. We show that the free biholomorphic classification of the domains is the same as the classification, up to unital completely isometric isomorphisms having completely contractive hereditary extension, of the corresponding noncommutative domain algebras A(D f, rad m ). In particular, we prove that Ψ : A(D f, rad 1 ) → A(D g, rad 1 ) is a unital completely isometric isomorphism if and only if there is a free biholomorphic map φ ∈ Bih(D g 1 , D f 1 ) such that This implies that the noncommutative domains and are free biholomorphic equivalent if and only if the domain algebras A(D f, rad 1 ) and A(D g, rad 1 ) are completely isometrically isomorphic. Using the interaction between the theory of functions in several complex variables and our noncommutative theory, we provide several results concerning the free biholomorphic classification of the noncommutative domains and the classification, up to completely isometric isomorphisms, of the associated noncommutative domain (resp. Hardy) algebras. In particular, we characterize the unit ball of among the noncommutative domains , up to free biholomorphisms. We also obtain characterizations for the unitarily implemented isomorphisms of noncommutative Hardy (resp. domain) algebras in terms of free biholomorphic functions between the corresponding noncommutative domains.

Let An (n = 2, 3, . . . , or n = ∞) be the noncommutative disc algebra, and On (resp. Tn) be the Cuntz (resp. Toeplitz) algebra on n generators. Minimal joint isometric dilations for families of contractive sequences of operators on a Hilbert space are obtained and used to extend the von Neumann inequality and the commutant lifting theorem to our noncommutative setting. We show that the universal algebra generated by k contractive sequences of operators and the identity is the amalgamated free product operator algebra ∗CAni for some positive integers n1, n2, . . . , nk ≥ 1, and characterize the completely bounded representations of ∗CAni . It is also shown that ∗CAni is completely isometrically imbedded in the “biggest” free product C∗-algebra ∗CTni (resp. ∗COni), and that all these algebras are completely isometrically isomorphic to some universal free operator algebras, providing in this way some factorization theorems. We show that the free product disc algebra ∗CAni is not amenable and the set of all its characters is homeomorphic to (C1)1 × · · · × (Ck)1. An extension of the Naimark dilation theorem to free semigroups is considered. This is used to construct a large class of positive definite operator-valued kernels on the unital free semigroup on n generators and to study the class Cρ (ρ > 0) of ρ-contractive sequences of operators. The dilation theorems are also used to extend the operatorial trigonometric moment problem to the free product C∗-algebras ∗CTni and ∗COni .

Let R be a prime ring, F be a generalized derivation associated with a derivation d of R and m, n be the fixed positive integers. In this paper we study the case when one of the following holds: (i) F(x) ◦m F(y) = (x ◦ y)n, (ii) F(x)◦md(y) = d(x◦y)n for all x, y in some appropriate subset of R. We also examine the case where R is a semiprime ring. Finally, as an application we obtain some range inclusion results of continuous or spectrally bounded generalized derivations on non-commutative Banach algebras.

Let R be a prime ring of characteristic different from 2 and m a fixed positive integer. If R admits a generalized derivation associated with a nonzero deviation d such that [F(x),d(y)] m =[x,y] for all x,y in some appropriate subset of R, then R is commutative. Moreover, we also examine the case R is a semiprime ring. Finally, we apply the above result to Banach algebras, and we obtain a non-commutative version of the Singer–Werner theorem.

Chapter 12 - Distances on Numbers, Polynomials, and Matrices