91 |
The Model Theory of Algebraically Closed FieldsCook, Daniel January 2000 (has links)
Model theory can express properties of algebraic subsets of complex n-space. The constructible subsets are precisely the first order definable subsets, and varieties correspond to maximal consistent collections of formulas, called types. Moreover, the topological dimension of a constructible set is equal to the Morley rank of the formula which defines it.
|
92 |
Matrix Formulations of Matching ProblemsWebb, Kerri January 2000 (has links)
Finding the maximum size of a matching in an undirected graph and finding the maximum size of branching in a directed graph can be formulated as matrix rank problems. The Tutte matrix, introduced by Tutte as a representation of an undirected graph, has rank equal to the maximum number of vertices covered by a matching in the associated graph. The branching matrix, a representation of a directed graph, has rank equal to the maximum number of vertices covered by a branching in the associated graph. A mixed graph has both undirected and directed edges, and the matching forest problem for mixed graphs, introduced by Giles, is a generalization of the matching problem and the branching problem. A mixed graph can be represented by the matching forest matrix, and the rank of the matching forest matrix is related to the size of a matching forest in the associated mixed graph. The Tutte matrix and the branching matrix have indeterminate entries, and we describe algorithms that evaluate the indeterminates as rationals in such a way that the rank of the evaluated matrix is equal to the rank of the indeterminate matrix. Matroids in the context of graphs are discussed, and matroid formulations for the matching, branching, and matching forest problems are given.
|
93 |
Improving Network Reliability: Analysis, Methodology, and AlgorithmsBooker, Graham B. 2010 May 1900 (has links)
The reliability of networking and communication systems is vital for the nation's
economy and security. Optical and cellular networks have become a critical infrastructure
and are indispensable in emergency situations. This dissertation outlines
methods for analyzing such infrastructures in the presence of catastrophic failures,
such as a hurricane, as well as accidental failures of one or more components. Additionally,
it presents a method for protecting against the loss of a single link in a
multicast network along with a technique that enables wireless clients to efficiently
recover lost data sent by their source through collaborative information exchange.
Analysis of a network's reliability during a natural disaster can be assessed by
simulating the conditions in which it is expected to perform. This dissertation conducts
the analysis of a cellular infrastructure in the aftermath of a hurricane through
Monte-Carlo sampling and presents alternative topologies which reduce resulting loss
of calls. While previous research on restoration mechanisms for large-scale networks
has mostly focused on handling the failures of single network elements, this dissertation
examines the sampling methods used for simulating multiple failures. We present
a quick method of nding a lower bound on a network's data loss through enumeration
of possible cuts as well as an efficient method of nding a tighter lower bound
through genetic algorithms leveraging the niching technique.
Mitigation of data losses in a multicast network can be achieved by adding redundancy
and employing advanced coding techniques. By using Maximum Rank Distance (MRD) codes at the source, a provider can create a parity packet which is
e ectively linearly independent from the source packets such that all packets may be
transmitted through the network using the network coding technique. This allows
all sinks to recover all of the original data even with the failure of an edge within
the network. Furthermore, this dissertation presents a method that allows a group of
wireless clients to cooperatively recover from erasures (e.g., due to failures) by using
the index coding techniques.
|
94 |
Applying Analytic Hierarchy Process to Mobile Phone RecommendationKuo, Ya-Ru 26 July 2004 (has links)
With the extension of the World Wide Web, more than 7 million new pages being exploited each day, the problem of information overload due to a large number of coping, spreading and sharing causes the decreasing information quantity, diverse format of information and low quality of information. More researchers research what methods including search and recommendation can help users gather the critical topics. Whatever methods use historical purchasing or browsing data to find the proper information usually, can not considering all attributes affecting decision results. Therefore, the research uses Analytic Hierarchy Process belonging Multiple Critical Decision Theory to develop recommendation system.
Providing a single, easy understand model, using hierarchic structuring reflecting the nature tendency of the mind, considering all attributes affecting decision results, Analytic Hierarchy Process takes into consideration the relative priorities and select the best alternative. Furthermore, it can show the subjective consciousness of the user in a structure way and assist designer to determine a more rational and conformable judgment. Based on Analytic Hierarchy Process, the commerce recommendation system expects to help user to find more satisfactory merchandise. It is found that the recommendation system using Analytic Hierarchy Process finds the accurate products for user and gets the higher satisfaction. However, the operation satisfaction is not higher that rank-based but still in available and satisfaction scope.
|
95 |
Dimensions and Integral ExtensionsTsai, Chung-Wen 28 July 2004 (has links)
Recently, Dawson and Feinstein showed that a Banach algebra integral extension B of a commutative
Banach algebra A of topological stable rank one is again of topological stable rank
one. In this thesis, we provide a partial converse to this statement: If an Arens-Hoffman extension
A® of a commutative C*-algebra A has topological stable rank one then A has topological
stable rank one.
|
96 |
Simple Groups Of Finite Morley Rank With A Tight Automorphism Whose Centralizer Is PseudofiniteUgurlu, Pinar 01 June 2009 (has links) (PDF)
This thesis is devoted to the analysis of relations between two major conjectures in the theory of groups of finite Morley rank. One of them is the Cherlin-Zil' / ber Algebraicity Conjecture which states that infinite simple groups of finite Morley rank are isomorphic to simple algebraic groups over algebraically closed fields. The other conjecture is due to Hrushovski and it states that a generic automorphism of a simple group of finite Morley rank has pseudofinite group of fixed points. Hrushovski showed that the Cherlin-Zil' / ber Conjecture implies his conjecture. Proving his Conjecture and reversing the implication would provide a new efficient approach to prove the Cherlin-Zil' / ber Conjecture.
This thesis proposes an approach to derive a proof of the Cherlin-Zil' / ber Conjecture from Hrushovski' / s Conjecture and contains a proof of a step in that direction. Firstly, we show that John S. Wilson' / s classification theorem for simple pseudofinite groups can be adapted for definably simple non-abelian pseudofinite groups of finite centralizer dimension. Combining this result with recent related developments, we identify definably simple non-abelian pseudofinite groups with Chevalley or twisted Chevalley groups over pseudofinite fields. After that in the context of Hrushovski' / s Conjecture, in a purely
algebraic set-up, we show that the pseudofinite group of fixed points of a generic automorphism is actually an extension of a Chevalley group or a twisted Chevalley group over a pseudofinite field.
|
97 |
On the consistency of a simulation procedure and the construction of a non-parametric test for interval-censored dataSen, Ching-Fu 14 June 2001 (has links)
In this paper, we prove that the simulation method for
interval-censored data proposed by Fay (1999) is consistent in the
sense that if we select a sample, then the estimate obtained from
Turnbulls (1974) EM algorithm will converge to the
true parameter when the sample size tends to infinity. We also
propose a non-parametric rank test for interval-censored data to
determine whether two populations come from the same distribution.
Simulation result shows that the proposed
test statistics performs pretty satisfactory.
|
98 |
Grooming Behavior of Formosan macaques (Macaca cyclopis) at Mt. Longevity, TaiwanLin, Tai-jung 06 February 2009 (has links)
I have investigated the social grooming in kinship, rank, age and seasonal change among adult female Formosan macaques (Macaca cyclopis) that inhabit Mt. Longevity, Kaohsiung. The major study groups were C and Cd groups. Field observations were conducted from August 2000 to February 2003 covering three mating seasons and two non-mating seasons. The observations covered a total of 188 work days including 1248.8 hours. I actually had recorded C group for 660.6 hours, and Cd group for 244.5 hours. During my study, C group consisted of 8-13 adult males and 14-15 adult females, while group Cd had 1-3 adult males and 2-4 adult females. In order to analyze grooming data, I divided 15 adult females into sub-groups such as dominant/ submissive groups, old (>13) /young age (5-12), relative higher/lower ranking and related/unrelated. I have also divided adult males into troop-males and periphery males.
Adult female allo-grooming activities accounted for 37.62% ¡Ó 13.59 (n = 15) of the behaviors in the daytime. I also found that adult females grooming infants and juveniles were greater than received from them (p < 0.001). The social grooming among adult females occurred mainly during non-mating seasons and its frequency was 2.12 times of mating seasons. Regardless of mating or non-mating seasons, the frequency of grooming among related females was significantly higher than among unrelated females (both p < 0.001). In addition, kinship affected the grooming frequency among female macaques with relative lower or higher ranking females during mating seasons (p < 0.05), while the dominant rank did not have the effect. However, the highest grooming frequency occurred in the high-ranking females who groomed relative lower ranking females within relatives (0.38 ¡Ó 0.40 bouts / 100 scans, n = 7). During non-mating seasons, kinship affected the grooming frequency among female macaques with relative lower ranking females (p < 0.05); the highest grooming frequency occurred in the old females who groomed relative lower ranking females within relatives (1.57 ¡Ó 1.74 bouts / 100 scans, n = 8).
Moreover, seasons (mating or non-mating) and kinship relationship had significant effects on grooming frequencies among female macaques (both giving and receiving p < 0.01), as well as on the grooming frequency of females groomed with relative lower ranking females (p < 0.01). The highest grooming frequency occurred on females groomed with relative lower ranking females within relatives during non-mating seasons (1.25 ¡Ó 1.48 bouts / 100 scans, n = 11).
Without kinship relationship, low-ranking females groomed relative higher ranking females more frequent than high-ranking females did (p < 0.05). Within adult females, 65% of social grooming was among relatives. However, 40% of adult females groomed equally with related and unrelated females, while 20% disproportionately groomed more with unrelated females than with related females. The grooming was kin-biased for 40%. About 8.68% of social grooming among unrelated females was being reciprocated.
On the other hand, the ratio of related grooming female partners to the total number of available related females was higher than that with unrelated females (p < 0.05). It also indicated that the ratio of each female received grooming from high-ranking grooming partners was higher than that from low-ranking females (p < 0.01).On the other hand, the ratio of the number of old or young grooming partners of adult females had similar values. The grooming frequency of adult females gave or received from adult males during mating seasons was higher than non-mating seasons (both p < 0.05) while high-rank females groomed adult males more than low-rank females did.
The socionomic sex ratios of these two social groups were similar during mating seasons (AM:AF = 1:1.8). Both troop and periphery males had significantly higher frequency of social grooming with adult females in mating seasons than in non-mating seasons. The types of males and social groups had significant effects on the allogrooming frequency among adult males in mating seasons (p < 0.05) but not in non-mating seasons (p > 0.1). Moreover, troop males had higher grooming partners than periphery males. Major grooming partners of troop males were adult females regardless of the seasons. Subordinate males were mostly the receivers in the grooming dyads with dominant males in the mating seasons, but the relationships changed during non-mating seasons. Agonistic interactions occurred mainly during mating seasons and its frequency among periphery males was 1.8 times of troop males (p < 0.05).
The preference grooming sites between allo-grooming and auto-grooming of C and Cd groups had varied significantly (p < 0.001). The back region was the preferred grooming site in allo-grooming of C and Cd group and the ano-genital region was the least groomed site. In auto-grooming, monkeys paid much attention to the legs ignoring the back and face. The result indicated that when the adult individuals groomed the head, back and face which showed significant difference in the frequency among AM and AF (p < 0.05). The related female adults groomed head more frequently than unrelated female adults (p < 0.05), but dominance rank and age-class did not apparently affect the corresponding values for the frequency of grooming sites among adult females (both p > 0.1).
The results indicated that social grooming among adult females took place more often during non-mating seasons, and more often in kin-related females than unrelated females. Moreover, the dominant females were likely to groom related females. Therefore social grooming among kin-related females may reinforce relationships while reciprocal grooming of unrelated females may serve to form alliance or ranking promotion in the social group. On the other hand, social grooming between adult male and female macaques more frequent in mating seasons than in non-mating seasons. This showed that adult male Formosan macaques employed complex strategies to achieve reproductive success. Nonetheless, the periphery males had more male grooming partners than troop males did which seemingly to enhance male coalitions.
|
99 |
Rank gradient in co-final towers of certain Kleinian groupsGirão, Darlan Rabelo 01 February 2012 (has links)
This dissertation provides the first known examples of finite co-volume Kleinian groups which have co- final towers of finite index subgroups with positive
rank gradient. We prove that if the fundamental group of an orientable finite volume hyperbolic 3-manifold has fi nite index in the reflection group of a
right-angled ideal polyhedron in H^3 then it has a co-fi nal tower of fi nite sheeted covers with positive rank gradient. The manifolds we provide are also known
to have co- final towers of covers with zero rank gradient. We also prove that the reflection groups of compact right-angled hyperbolic polyhedra satisfying mild conditions have co-fi nal towers of fi nite sheeted covers with positive rank gradient. / text
|
100 |
Remote-Sensed LIDAR Using Random Impulsive ScansCastorena, Juan 10 1900 (has links)
Third generation full-waveform (FW) LIDAR systems image an entire scene by emitting laser pulses in particular directions and measuring the echoes. Each of these echoes provides range measurements about the objects intercepted by the laser pulse along a specified direction. By scanning through a specified region using a series of emitted pulses and observing their echoes, connected 1D profiles of 3D scenes can be readily obtained. This extra information has proven helpful in providing additional insight into the scene structure which can be used to construct effective characterizations and classifications. Unfortunately, massive amounts of data are typically collected which impose storage, processing and transmission limitations. To address these problems, a number of compression approaches have been developed in the literature. These, however, generally require the initial acquisition of large amounts of data only to later discard most of it by exploiting redundancies, thus sampling inefficiently. Based on this, our main goal is to apply efficient and effective LIDAR sampling schemes that achieve acceptable reconstruction quality of the 3D scenes. To achieve this goal, we propose on using compressive sampling by emitting pulses only into random locations within the scene and collecting only the corresponding returned FW signals. Under this framework, the number of emissions would typically be much smaller than what traditional LIDAR systems require. Application of this requires, however, that scenes contain many degrees of freedom. Fortunately, such a requirement is satisfied in most natural and man-made scenes. Here, we propose to use a measure of rank as the measure of degrees of freedom. To recover the connected 1D profiles of the 3D scene, matrix completion is applied to the tensor slices. In this paper, we test our approach by showing that recovery of compressively sampled 1D profiles of actual 3D scenes is possible using only a subset of measurements.
|
Page generated in 0.0574 seconds