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

We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

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Convex Analysisの二,三の進展について

Data integration is the problem of combining data residing at different sources, and providing the user with a unified view of these data. The problem of designing data integration systems is important in current real world applications, and is characterized by a number of issues that are interesting from a theoretical point of view. This document presents on overview of the material to be presented in a tutorial on data integration. The tutorial is focused on some of the theoretical issues that are relevant for data integration. Special attention will be devoted to the following aspects: modeling a data integration application, processing queries in data integration, dealing with inconsistent data sources, and reasoning on queries.

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Data integration: a theoretical perspective

Optimization, approximation, and complexity classes

Databases are ubiquitous in our society. This dissertation presents a complexity analysis of two important problems related to databases. First, we show the complexity of establishing strong k-consistency, which is a common heuristic for database query evaluation. Second, we classify the complexity of the existence-of-solutions problem for data exchange. 
The first part of this dissertation presents a computational complexity analysis of the problem of determining the winner of the existential k-pebble game. Existential k-pebbles were originally introduced to aid in the analysis of the expressive power of Datalog and related infinitary logics with finitely many variables. It has since been observed that strong k-consistency can be established for an instance of constraint satisfaction if and only if the Duplicator has a winning strategy for the existential k-pebble game on structures related to the given instance of constraint satisfaction. The main result is that determining the winner of the existential k-pebble game is EXPTIME-complete when k is part of the input. This implies that establishing strong k-consistency is inherently exponential. We then use this result to prove complexity results for a collection of related games. 
The second part of this dissertation addresses the combined complexity of the existence-of-solutions problem for data exchange. Data exchange is the problem of transforming data from a source schema to a target schema so that all constraints of a schema mapping are satisfied. The existence-of-solutions problem is the question: given a source instance, is there a target instance that satisfies the constraints of the schema mapping? Earlier work showed that for schema mappings specified by embedded implicational dependencies, this problem is solvable in polynomial time, if the schema mapping is fixed and the constraints of the schema mapping satisfy a certain structural condition, called weak acyclicity. We show that if the schema mapping is also part of the input, then the complexity of the existence-of-solutions problem rises to 2EXPTIME. We also show that there are restricted classes of inputs to the existence-of-solutions problem for which the problem can be EXPTIME-complete or CoNP-complete.

Complexity in databases, games, and logics

of invited panel discussion PANELISTS: KIM B. BRUCE, PETER B. HENDERSON, DANIEL LEIVANT, AND JOHN S. SCHLIPF, Panel discussion on logic in computer science education. Department of Computer Science, Williams College, Williamstown, MA 01267. E-mail: kim@cs.williams.edu. Department of Computer Science and Software Engineering, Butler University, 4600 Sunset Avenue, Indianapolis, IN 46208-3485. E-mail: phenders@butler.edu. Department of Computer Science, Indiana University Bloomington, Bloomington, IN 47405. E-mail: leivant@cs.indiana.edu. Department of Electrical and Computer Engineering and Computer Science, University of Cincinnati, Cincinnati, OH 45221. E-mail: john.schlipf@uc.edu. Logic is as important in computer science as calculus is in the natural science and traditional engineering fields. Yet many curricula play only lip service to its role, with logic being touched on in a discrete mathematics course that is usually poorly integrated with the rest of the computing curriculum. We argue that topics in logic should pervade the computing curriculum and point out courses where logic should play a major role. The courses and topics involving logic include architecture (logic gates), software engineering (modeling, specification and verification), programming languages (types, semantics, logic programming), database (relational algebra and SQL), artificial intelligence (automatic theorem proving, knowledge representation, and commonsense reasoning), algorithms (complexity and expressiveness), and theory of computation (general notions of computability). Questions to be addressed include: – What depth of logical knowledge is required of CS students? – When and how should we teach logic (e.g., in a separate logic or discrete math course or integrated with computer science topics)? – What materials and courseware are available and useful for teaching logic? – How can we help students understand the importance of logical concepts to computer science? – How can logic be reinforced throughout the CS curriculum? – Should logic be presented to CS students differently than to mathematics and philosophy students?

Panel: logic in the computer science curriculum

We investigate phase transitions for the family of bounded satisfiability problems 3SAT(b), recently introduced by Zhang, that ask: given a 3CNF- formula, is there a truth assignment that violates no more than b of its clauses. Zhang's results were experimental and for a fixed number of variables (n = 25), and suggested that the locations of the phase transitions for 3SAT(b) are separated and move significantly as b increases. Analysis of these locations was posed as an open question.

We analytically show that the phase transitions of all 3SAT(6) problems must occur within a narrow region, regardless of how large the value of b is. Moreover, our experiments reveal that the phase transitions for these problems occur in a remarkable way. Specifically, unlike 3SAT, the probability curves for 3SAT(6) do not have a quasi-common intersection point about which they rotate as they become steeper with increasing n. Instead, they move rapidly to the left toward the narrow region that the analysis predicts.

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Phase transitions of bounded satisfiability problems

This report documents the program and the outcomes of Dagstuhl Seminar 17361 "Finite and Algorithmic Model Theory".

Finite and Algorithmic Model Theory (Dagstuhl Seminar 17361)

Schema mappings are high-level specifications that describe the relationship between two database schemas. Schema mappings are considered to be the essential building blocks in such critical data interoperability tasks as data exchange and data integration. For this reason, they have been the focus of extensive research investigations over the past several years. Since in real-life applications schema mappings can be quite complex, it is important to develop methods and tools for illustrating, explaining, and deriving schema mappings. A promising approach to this eect is to use “good” data examples that illustrate the schema mapping at hand. In this talk, we present an overview of recent work on characterizing and deriving schema mappings via a finite set of data examples. We show that every LAV schema mapping (i.e., a schema mapping specified by a finite set of local-as-view tuple-generating dependencies) is uniquely characterized by a finite set of universal data examples with respect to the class of all LAV schema mappings. We also show that this type of result does not hold for arbitrary GAV schema mappings (i.e., schema mappings specified by a finite set of global-as-view tuplegenerating dependencies). After this, we give a necessary and sucient

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Phokion G. Kolaitis

Papers

Complexity in databases, games, and logics

Panel: logic in the computer science curriculum

Phase transitions of bounded satisfiability problems

Finite and Algorithmic Model Theory (Dagstuhl Seminar 17361)

Schema Mappings and Data Examples: Deriving Syntax from Semantics