Diss.--Europäisches Hochinstitut--Florenz, 1988.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

We consider and solve some open conjectures on the asymptotic behavior of the number of different numbers of the nonassociate factorizations of prescribed minimal length for specific finite factorization domains. The asymptotic behavior will be classified for Cohen-Kaplansky domains in Chapter 1 and for domains of the form R=K+XF[X] for finite fields K and F in Chapter 2. A corollary of the main result in Chapter 3 will determine the asymptotic behavior for Krull domains with finite divisor class group.

The main purpose of this paper is to better understand groups that do not have the unique product property. In particular, the goal is to better understand Promislow's example, G, of such a group. In doing so, we will develop methods for generating examples of other sets that do not have the unique product property. With these methods we can show that there exists other distinct 14 element, square, non-unique product sets in G that are not inversions or translations. Also, this paper answers the question as to whether every non-unique product set can have only 14 elements in the negative by producing a 17 element square n.u.p. set. The secondary purpose of this paper is to demonstrate that in the group ring K[G], there are no units of support size 3. / Master of Science

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Créée en 1954, la taxe sur la valeur ajoutée a toujours été présentée comme un impôt difficile à frauder en raison de la règle du paiement fractionné qui incite à rapprocher les déclarations effectuées par les opérateurs. Malgré cette qualité originelle, la TVA est actuellement l’impôt qui engendre les plus fortes pertes dans l’Union européenne. Ceci est révélateur d’un système d’imposition qui n’a pas su s’adapter à l’évolution de la construction européenne et à l’apparition des nouvelles technologies. Malgré cela, il est évident que les détournements en matière de TVA ont une cause plus profonde qui réside dans le rôle de collecteur d’impôt confié aux entreprises. Pour remédier au fléau de la fraude, plusieurs solutions sont envisageables. S’il est indispensable, comme le souhaite la Commission européenne, d’évoluer vers un système définitif de TVA prévoyant une taxation des opérations intracommunautaires, cette approche doit se combiner avec une modernisation de l’impôt. Les nouvelles technologies offrent désormais de nombreuses opportunités pour sécuriser les échanges et rendre le système étanche à la fraude. / Established in 1954, the value-added tax has always been considered as a levy that is not easily defrauded because of the divided payment rule that encourages bringing closer the reportings done by the operators. In spite of that original ability, the VAT is currently the tax that makes the most important losses within the European Union. This reveals that this taxation system could not adjust to the evolution of the European construction and to the emergence of new technologies. Despite this, it is obvious that the embezzlements concerning the VAT have a much more sizable cause that lies in the tax collector’s role given to the companies. To rectify the scourge that is the fraud, several solutions are intended. If it is necessary, as the European Commission wishes, to move towards a definitive system of VAT planning taxation on the intercommunity operations, this perspective must combine with an upgrading of the levy. The new technologies henceforth offer numerous opportunities to secure the exchanges and make the system hermetic to the fraud.

Pars 1 and 2 are devoted to study of solutions of certain differential inequalities. Namely, in Part 1 we show that a germ of an analytic set (real or complex) admits a Gagliardo-Nirenberg type inequality with a certain exponent s>=1. At a regular point s=1, and the inequality becomes classical. As our examples show, s can be strictly greater than 1 even for an isolated singularity. In Part 2 we prove the property of unique continuation for solutions of differential inequality |\Delta u|<=|Vu| for a large class of potentials V. This result can be applied to the problem of absence of positive eigenvalues for self-adjoint Schroedinger operator -\Delta+V defined in the sense of the form sum. The results of Part 2 are joint with Leonid Shartser. In Parts 3 and 4 we derive the basic elements of complex function theory within some subalgebras of holomorphic functions (including extension from submanifolds, corona type theorem, properties of divisors, approximation property). Our key instruments and results are the analogues of Cartan theorems A and B for the `coherent sheaves' on the maximal ideal spaces of these subalgebras, and of Oka-Cartan theorem on coherence of the sheaves of ideals of the corresponding complex analytic subsets. More precisely, in Part 3 we consider the algebras of holomorphic functions on regular coverings of complex manifolds whose restrictions to each fiber belong to a translation-invariant Banach subalgebra of bounded functions endowed with sup-norm. The model examples of such subalgebras are Bohr's holomorphic almost periodic functions on tube domains, and all fibrewise bounded holomorphic functions on regular coverings of complex manifolds. In Part 4 the primary object of study is the subalgebra of bounded holomorphic functions on the unit disk whose moduli can have only boundary discontinuities of the first kind. The results of Parts 3 and 4 are joint with Alexander Brudnyi.

Pars 1 and 2 are devoted to study of solutions of certain differential inequalities. Namely, in Part 1 we show that a germ of an analytic set (real or complex) admits a Gagliardo-Nirenberg type inequality with a certain exponent s>=1. At a regular point s=1, and the inequality becomes classical. As our examples show, s can be strictly greater than 1 even for an isolated singularity. In Part 2 we prove the property of unique continuation for solutions of differential inequality |\Delta u|<=|Vu| for a large class of potentials V. This result can be applied to the problem of absence of positive eigenvalues for self-adjoint Schroedinger operator -\Delta+V defined in the sense of the form sum. The results of Part 2 are joint with Leonid Shartser. In Parts 3 and 4 we derive the basic elements of complex function theory within some subalgebras of holomorphic functions (including extension from submanifolds, corona type theorem, properties of divisors, approximation property). Our key instruments and results are the analogues of Cartan theorems A and B for the `coherent sheaves' on the maximal ideal spaces of these subalgebras, and of Oka-Cartan theorem on coherence of the sheaves of ideals of the corresponding complex analytic subsets. More precisely, in Part 3 we consider the algebras of holomorphic functions on regular coverings of complex manifolds whose restrictions to each fiber belong to a translation-invariant Banach subalgebra of bounded functions endowed with sup-norm. The model examples of such subalgebras are Bohr's holomorphic almost periodic functions on tube domains, and all fibrewise bounded holomorphic functions on regular coverings of complex manifolds. In Part 4 the primary object of study is the subalgebra of bounded holomorphic functions on the unit disk whose moduli can have only boundary discontinuities of the first kind. The results of Parts 3 and 4 are joint with Alexander Brudnyi.

Bangladesh geographically comprised one of the largest delta landscapes of the world. Almost 6.7% of country’stotal area (147570 sqkm.) is covered byrivers and inland water bodies. These water bodies being rich in fishproduction meet the majority of the demand of protein. Bangladesh produces world's fourth largest quantity of fishand it is collected from the inland water bodies. Though shrimps were easily available in the inland water bodies forhundreds of years but shrimp culture as an export-oriented activity is a phenomenon of recent past. Bangladeshearned US$ 2.9 million by exporting shrimp in 1972-73 which was 1 % of the country's total exports. It increased to US$ 33 million in 1980 and to US$ 90.0 million in 1985. But until the mid-1980’s shrimp culture was principallydependent on open-water catches of shrimp it means that time shrimps were not cultivated in a proper planned way.But the culture of shrimp totally for export purpose started after the mid 1980’s. Since then the professional cultivation of shrimp had a very positive and effective impact on the economy of Bangladesh. Exports of shrimpfrom Bangladesh increased from US$ 91 million in FY (Fiscal Year) 1986 to US$ 280 million in FY1997. Duringthe corresponding period, the quantity of shrimp exports increased from 17.2 thousand tonnes to 25.2 thousandtonnes. As most of the shrimp farms have been developed without considering the sustainability of the environmentand some other factors like water pH &amp; salinity, soil pH &amp; salinity, soil texture etc. the farmers are getting lessreturn but affecting the environment most. Geographical Information System (GIS) can give an easier but effectivesolution here through selecting the best suitable sites for shrimp cultivation. Moreover GIS can solve thetransportation problem of this perishable product from the production area to the harbor or airport through transport route selection. This cansave a lot of money and time and consequently make the shrimp cultivation moreeconomic.

Mémoire--Genève--Institut universitaire de hautes études internationales, 1987. N°: 271. / Bibliogr. p. I-XII.