Multiple-Environment Markov Decision Processes

We introduce Multi-Environment Markov Decision Processes (MEMDPs) which are MDPs with a set of probabilistic transition functions. The goal in a MEMDP is to synthesize a single controller with guaranteed performances against all environments even though the environment is unknown a priori. While MEMDPs can be seen as a special class of partially observable MDPs, we show that several verification problems that are undecidable for partially observable MDPs, are decidable for MEMDPs and sometimes have even efficient solutions

Online Correlation Clustering

We study the online clustering problem where data items arrive in an online fashion. The algorithm maintains a clustering of data items into similarity classes. Upon arrival of v, the relation between v and previously arrived items is revealed, so that for each u we are told whether v is similar to u. The algorithm can create a new cluster for v and merge existing clusters. When the objective is to minimize disagreements between the clustering and the input, we prove that a natural greedy algorithm is O(n)-competitive, and this is optimal. When the objective is to maximize agreements between the clustering and the input, we prove that the greedy algorithm is .5-competitive; that no online algorithm can be better than .834-competitive; we prove that it is possible to get better than 1/2, by exhibiting a randomized algorithm with competitive ratio .5+c for a small positive fixed constant c.Comment: 12 pages, 1 figur

Assume-Admissible Synthesis

In this paper, we introduce a novel rule for synthesis of reactive systems, applicable to systems made of n components which have each their own objectives. It is based on the notion of admissible strategies. We compare our novel rule with previous rules defined in the literature, and we show that contrary to the previous proposals, our rule defines sets of solutions which are rectangular. This property leads to solutions which are robust and resilient. We provide algorithms with optimal complexity and also an abstraction framework.Comment: 31 page

Impact of Community Level Engagement in Primary Education: A Case Study of Oyam District, Northern Uganda, Uganda, East Africa

This study was premised on the basis that primary education is the basic building block for a good quality of life in adult life. It specifically focuses on community level engagement in primary education. The broad research question of this thesis is how can community level engagement be enhanced to improve performance in primary schools? In order to answer this question, three primary objectives of this thesis were to assess the extent which community members are involved in the educational activities focusing the education in primary schools; to ascertain how community members have been involved in various educational activities, and to propose how can community level engagement can be enhanced to improve performance in primary schools. A case study research design was used in the study, and Oyam district was chosen as the case study to represent northern Uganda. The study used both qualitative and quantitative methods of data collection. Interview guides were used to generate qualitative data and questionnaires were used to generate quantitative data. The study findings showed that the level of community involvement is low, that is, only 21.7% of the community members interviewed were involved in school activities. It was established that community level engagement in primary education could be enhanced through sensitization of the community members about the importance of being actively involved in the activities of the school

Correlation of DNA double strand break repair efficiency and susceptibility to lung tumor development

2015 Spring.Includes bibliographical references.In this dissertation we describe the use of many CcS/Dem recombinant congenic strains (RCS) of mice to determine if there is any correlation between the DNA double strand break (DSB) repair efficiency and susceptibility to lung tumor development. A previous study involving 20 different CcS/Dem RCS of mice all derived from cross of BALB/c x STS progenitors (BALB/c is the recipient strain that is susceptible to tumor development and STS the donor is resistant) showed wide inter-strain variations in susceptibility to radiation-induced lung tumor development. As formalin fixation was used to obtain paraffin embedded tissue sections for immunofluorescence, we first evaluated different methods of euthanasia, perfusion techniques, autofluorescence reduction and antigen retrieval methods to optimize the procedures used so as to obtain reproducible results. The formation of phosphorylated histone H2AX (γ-H2AX) into discrete foci was used as the marker for DSB repair and its co-localization with 53BP1, another component of repair foci, was examined during the optimization. From the optimization phase, CO₂ asphyxiation, right ventricular perfusion, use of sodium borohydride for quenching autofluorescence and the use of sodium citrate for heat-induced epitope retrieval (antigen retrieval) gave very good quality images and were adopted for use in all subsequent experiments. To explore a possible link between heritable differences in DNA DSB repair efficiency and susceptibility to RI lung cancer in a mouse model, we quantified residual γH2AX foci in lungs of 16 different CcS/Dem RCS mice together with their founders after irradiation from a ¹³⁷Cs source of γ-rays at a low-dose rate of 10 cGy/hr for 24 h. We also explored residual γH2AX foci in the peripheral blood leukocytes to compare it with foci in the lungs with the intention of using PBLs as a surrogate to assess DNA repair efficiency in the lungs for possible use in clinical applications to pre-screening patients and assess their suitability as candidates for radiotherapy, especially in fairly young. In the lungs, the results showed a high correlation between mean residual γH2AX foci number per nucleus and radiation-induced lung tumor observed in the previous study (R=0.968, p t transition resulting in amino acid substitution that abolishes a BsmBI restriction site. The outcome of these restriction patterns suggests no direct correlation between DNA-PK and DSB repair efficiency and that another gene (or other genes) polymorphic between BALB/c and STS/A may determine the strain differences in DSB repair efficiencies

Compositional Algorithms for Succinct Safety Games

We study the synthesis of circuits for succinct safety specifications given in the AIG format. We show how AIG safety specifications can be decomposed automatically into sub specifications. Then we propose symbolic compositional algorithms to solve the synthesis problem compositionally starting for the sub-specifications. We have evaluated the compositional algorithms on a set of benchmarks including those proposed for the first synthesis competition organised in 2014 by the Synthesis Workshop affiliated to the CAV conference. We show that a large number of benchmarks can be decomposed automatically and solved more efficiently with the compositional algorithms that we propose in this paper.Comment: In Proceedings SYNT 2015, arXiv:1602.0078

AbsSynthe: abstract synthesis from succinct safety specifications

In this paper, we describe a synthesis algorithm for safety specifications described as circuits. Our algorithm is based on fixpoint computations, abstraction and refinement, it uses binary decision diagrams as symbolic data structure. We evaluate our tool on the benchmarks provided by the organizers of the synthesis competition organized within the SYNT'14 workshop.Comment: In Proceedings SYNT 2014, arXiv:1407.493

Tectonic environments and rare metal mineralization in pegmatites of Komu Area, Southwestern Nigeria

The discrimination diagrams: Rb versus Nb +Y and Nb versus Y, and Th/Ta ratio combined with field observations and empirical information from the literature were used to infer the tectonic environments and sources of the rare metal mineralization in the pegmatites of Komu area, southwestern Nigeria. The discrimination diagrams show that the pegmatites were mainly emplaced in tectonic environments similar to those of syn-collisional granites (Syn COG) and within plate granites (WPG). Volcanic arc environment was not pronounced. The emplacement of the pegmatites was structurally controlled by the predominantly Northeast (NE)– Southwest (SW) and North northeast (NNE)-South southwest (SSW) fault systems that were developed during the Pan-African orogeny. The upwelling of the mantle at the beginning and faulting systems associated with the active and closing stages of the Pan-African orogeny elevated rare metals from the mantle to higher crustal levels where they were incorporated into the pegmatitic fluids. The Th/Ta ratios of less than 1.00 which resemble that of the oceanic ridge tectonic environment is attributable to the upwelling of mantle material. The variation in the tectonic environments of the pegmatites may be attributed to the long span of the Pan-African orogeny (750-450 Ma).KEY WORDS: Komu. Nigeria. Pegmatites. Rare metals. Tectonic environments