Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The MAGMA algebra system I: the user language

The unreasonable effectiveness of quantum computing is founded on coherent quantum superposition or entanglement which allows a large number of calculations to be performed simultaneously. This coherence is lost as a quantum system interacts with its environment. In the present paper the problem of finding quantum-error-correcting codes is transformed into one of finding additive codes over the field GF(4) which are self-orthogonal with respect to a certain trace inner product. Many new codes and new bounds are presented, as well as a table of upper and lower bounds on such codes of length up to 30 qubits.

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Quantum error correction via codes over GF(4)

/pdf/handbook-of-magma-functions-5anhrdxxj3.pdf

Handbook of magma functions

This book is about the computational aspects of invariant theory. Of central interest is the question how the invariant ring of a given group action can be calculated. Algorithms for this purpose form the main pillars around which the book is built. There are two introductory chapters, one on Grobner basis methods and one on the basic concepts of invariant theory, which prepare the ground for the algorithms. Then algorithms for computing invariants of finite and reductive groups are discussed. Particular emphasis lies on interrelations between structural properties of invariant rings and computational methods. Finally, the book contains a chapter on applications of invariant theory, covering fields as disparate as graph theory, coding theory, dynamical systems, and computer vision. The book is intended for postgraduate students as well as researchers in geometry, computer algebra, and, of course, invariant theory. The text is enriched with numerous explicit examples which illustrate the theory and should be of more than passing interest. More than ten years after the first publication of the book, the second edition now provides a major update and covers many recent developments in the field. Among the roughly 100 added pages there are two appendices, authored by Vladimi r Popov, and an addendum by Norbert A'Campo and Vladimir Popov.

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Computational Invariant Theory

Nous demontrons une complexite polynomiale en temps pour l'algorithme de van Hoeij de factorisation de polynomes univaries a coefficients rationnels, ainsi que pour des variantes naturelles. En particulier, notre approche fournit aussi une complexite polynomiale pour les polynomes bivaries sur un corps fini.

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Factoring polynomials over global fields

We present algorithms which calculate the invariant ring K[V] G of a finite group G Our focus of interest lies on the modular case, ie, the case where |G| is divided by the characteristic of K We give easy algorithms to compute several interesting properties of the invariant ring, such as the Cohen-Macaulay property, depth, the β-number and syzygies

Allan Steel

Papers

Handbook of magma functions

Factoring polynomials over global fields

Some Algorithms in Invariant Theory of Finite Groups

Conquering inseparability: Primary decomposition and multivariate factorization over algebraic function fields of positive characteristic

A new algorithm for the computation of canonical forms of matrices over fields