360 research outputs found

    NLC-2 graph recognition and isomorphism

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    NLC-width is a variant of clique-width with many application in graph algorithmic. This paper is devoted to graphs of NLC-width two. After giving new structural properties of the class, we propose a O(n2m)O(n^2 m)-time algorithm, improving Johansson's algorithm \cite{Johansson00}. Moreover, our alogrithm is simple to understand. The above properties and algorithm allow us to propose a robust O(n2m)O(n^2 m)-time isomorphism algorithm for NLC-2 graphs. As far as we know, it is the first polynomial-time algorithm.Comment: soumis \`{a} WG 2007; 12

    Wiretapping a hidden network

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    We consider the problem of maximizing the probability of hitting a strategically chosen hidden virtual network by placing a wiretap on a single link of a communication network. This can be seen as a two-player win-lose (zero-sum) game that we call the wiretap game. The value of this game is the greatest probability that the wiretapper can secure for hitting the virtual network. The value is shown to equal the reciprocal of the strength of the underlying graph. We efficiently compute a unique partition of the edges of the graph, called the prime-partition, and find the set of pure strategies of the hider that are best responses against every maxmin strategy of the wiretapper. Using these special pure strategies of the hider, which we call omni-connected-spanning-subgraphs, we define a partial order on the elements of the prime-partition. From the partial order, we obtain a linear number of simple two-variable inequalities that define the maxmin-polytope, and a characterization of its extreme points. Our definition of the partial order allows us to find all equilibrium strategies of the wiretapper that minimize the number of pure best responses of the hider. Among these strategies, we efficiently compute the unique strategy that maximizes the least punishment that the hider incurs for playing a pure strategy that is not a best response. Finally, we show that this unique strategy is the nucleolus of the recently studied simple cooperative spanning connectivity game

    Two-sided combinatorial volume bounds for non-obtuse hyperbolic polyhedra

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    We give a method for computing upper and lower bounds for the volume of a non-obtuse hyperbolic polyhedron in terms of the combinatorics of the 1-skeleton. We introduce an algorithm that detects the geometric decomposition of good 3-orbifolds with planar singular locus and underlying manifold the 3-sphere. The volume bounds follow from techniques related to the proof of Thurston's Orbifold Theorem, Schl\"afli's formula, and previous results of the author giving volume bounds for right-angled hyperbolic polyhedra.Comment: 36 pages, 19 figure

    Cluster Editing: Kernelization based on Edge Cuts

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    Kernelization algorithms for the {\sc cluster editing} problem have been a popular topic in the recent research in parameterized computation. Thus far most kernelization algorithms for this problem are based on the concept of {\it critical cliques}. In this paper, we present new observations and new techniques for the study of kernelization algorithms for the {\sc cluster editing} problem. Our techniques are based on the study of the relationship between {\sc cluster editing} and graph edge-cuts. As an application, we present an O(n2){\cal O}(n^2)-time algorithm that constructs a 2k2k kernel for the {\it weighted} version of the {\sc cluster editing} problem. Our result meets the best kernel size for the unweighted version for the {\sc cluster editing} problem, and significantly improves the previous best kernel of quadratic size for the weighted version of the problem

    Severe Paediatric Asthma Collaborative in Europe (SPACE):protocol for a European registry

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    The development of new asthma biologics and receptor blockers for the treatment of paediatric severe asthma raises challenges. It is unclear whether there are sufficient children in Europe to recruit into randomised placebo-controlled trials to establish efficacy and safety in this age group. In February 2016, the European Respiratory Society funded a clinical research collaboration entitled “Severe Paediatric Asthma Collaborative in Europe” (SPACE). We now report the SPACE protocol for a prospective pan-European observational study of paediatric severe asthma. Inclusion criteria are: 1) age 6–17 years, 2) severe asthma managed at a specialised centre for ≥6 months, 3)clinical and spirometry evidence of asthma, and 4) reaching a pre-defined treatment threshold. The exclusion criterion is the presence of conditions which mimic asthma symptoms. Eligible children will be prospectively recruited into a registry, recording demographics, comorbidities, quality of life, family history, neonatal history, smoking history, asthma background, investigations, and treatment. Follow-up will provide longitudinal data on asthma control and treatment changes. The SPACE registry, by identifying well-phenotyped children eligible for clinical trials, and the amount of overlap in eligibility criteria, will inform the design of European trials in paediatric severe asthma, and facilitate observational research where data from single centres are limited

    Peri-operative chemotherapy with or without bevacizumab in operable oesophagogastric adenocarcinoma (UK Medical Research Council ST03): primary analysis results of a multicentre, open-label, randomised phase 2–3 trial

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    Background: Peri-operative chemotherapy and surgery is a standard of care for patients with resectable oesophagogastric adenocarcinoma. Bevacizumab, a monoclonal antibody against VEGF, improves the proportion of patients responding to treatment in advanced gastric cancer. We aimed to assess the safety and efficacy of adding bevacizumab to peri-operative chemotherapy in patients with resectable gastric, oesophagogastric junction, or lower oesophageal adenocarcinoma. Methods: In this multicentre, randomised, open-label phase 2–3 trial, we recruited patients aged 18 years and older with histologically proven, resectable oesophagogastric adenocarcinoma from 87 UK hospitals and cancer centres. We randomly assigned patients 1:1 to receive peri-operative epirubicin, cisplatin, and capecitabine chemotherapy or chemotherapy plus bevacizumab, in addition to surgery. Patients in the control group (chemotherapy alone) received three pre-operative and three post-operative cycles of epirubicin, cisplatin, and capecitabine chemotherapy: 50 mg/m2 epirubicin and 60 mg/m2 cisplatin on day 1 and 1250 mg/m2 oral capecitabine on days 1–21. Patients in the investigational group received the same treatment as the control group plus 7·5 mg/kg intravenous bevacizumab on day 1 of every cycle of chemotherapy and for six further doses once every 21 days following chemotherapy, as maintenance treatment. Randomisation was done by means of a telephone call to the Medical Research Council Clinical Trials Unit, where staff used a computer programme that implemented a minimisation algorithm with a random element to establish the allocation for the patient at the point of randomisation. Patients were stratified by chemotherapy centre, site of tumour, and tumour stage. The primary outcome for the phase 3 stage of the trial was overall survival (defined as the time from randomisation until death from any cause), analysed in the intention-to-treat population. Here, we report the primary analysis results of the trial; all patients have completed treatment and the required number of primary outcome events has been reached. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN 46020948, and with ClinicalTrials.gov, number NCT00450203. Findings: Between Oct 31, 2007, and March 25, 2014, 1063 patients were enrolled and randomly assigned to receive chemotherapy alone (n=533) or chemotherapy plus bevacizumab (n=530). At the time of analysis, 508 deaths were recorded (248 in the chemotherapy alone group and 260 in the chemotherapy plus bevacizumab group). 3-year overall survival was 50·3% (95% CI 45·5–54·9) in the chemotherapy alone group and 48·1% (43·2–52·7) in the chemotherapy plus bevacizumab group (hazard ratio [HR] 1·08, 95% CI 0·91–1·29; p=0·36). Apart from neutropenia no other toxic effects were reported at grade 3 or worse severity in more than 10% of patients in either group. Wound healing complications were more prevalent in the bevacizumab group, occurring in 53 (12%) patients in this group compared with 33 (7%) patients in the chemotherapy alone group. In patients who underwent oesophagogastrectomy, post-operative anastomotic leak rates were higher in the chemotherapy plus bevacizumab group (23 [10%] of 233 in the chemotherapy alone group vs 52 [24%] of 220 in the chemotherapy plus bevacizumab group); therefore, recruitment of patients with lower oesophageal or junctional tumours planned for an oesophagogastric resection was stopped towards the end of the trial. Serious adverse events for all patients included anastomotic leaks (30 events in chemotherapy alone group vs 69 in the chemotherapy plus bevacizumab group), and infections with normal neutrophil count (42 events vs 53). Interpretation: The results of this trial do not provide any evidence for the use of bevacizumab in combination with peri-operative epiribicin, cisplatin, and capecitabine chemotherapy for patients with resectable gastric, oesophagogastric junction, or lower oesophageal adenocarcinoma. Bevacizumab might also be associated with impaired wound healing. Funding: Cancer Research UK, MRC Clinical Trials Unit at University College London, and F Hoffmann-La Roche Limited

    An update on the Hirsch conjecture

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    The Hirsch conjecture was posed in 1957 in a letter from Warren M. Hirsch to George Dantzig. It states that the graph of a d-dimensional polytope with n facets cannot have diameter greater than n - d. Despite being one of the most fundamental, basic and old problems in polytope theory, what we know is quite scarce. Most notably, no polynomial upper bound is known for the diameters that are conjectured to be linear. In contrast, very few polytopes are known where the bound ndn-d is attained. This paper collects known results and remarks both on the positive and on the negative side of the conjecture. Some proofs are included, but only those that we hope are accessible to a general mathematical audience without introducing too many technicalities.Comment: 28 pages, 6 figures. Many proofs have been taken out from version 2 and put into the appendix arXiv:0912.423

    Ketidakoptimalan Penanganan Perkara Pidana Rehabilitasi Penyalahguna Narkotika di Wilayah Hukum Kejaksaan Negeri Mejayan Kabupaten Madiun

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    ABSTRAK Rahmat Hidayat S331302008, 2015, Ketidakoptimalan Penanganan Perkara Pidana Rehabilitasi Penyalahguna Narkotika di Wilayah Hukum Kejaksaan Negeri Mejayan Kabupaten Madiun. Tujuan dari penulisan tesis ini yaitu pelaksanaan rehabilitasi bagi penyalahguna narkotika yang belum dilaksanakan dan upaya yang dilakukan agar rehabilitasi secara optimal dilaksanakan di wilayah hukum Kejaksaan Negeri Mejayan Kabupaten Madiun. Adapun rumusan masalah yang diangkat dalam penulisan tesis ini adalah Mengapa rehabilitasi bagi penyalahguna narkotika di wilayah Hukum Kejaksaan Negeri Mejayan Kabupaten Madiun belum dilaksanakan secara optimal dan Upaya apa yang suharusnya dilakukan agar rehabilitasi penyalahguna narkotika di wilayah Hukum Kejaksaan Negeri Mejayan Kabupaten Madiun dilaksanakan secara optimal. Penelitian dalam tesis ini adalah penelitian hukum yuridis normatif dan yuridis empiris, jenis pendekatan yang dipergunakan dalam penulisan tesis ini adalah kualitatif adalah suatu cara analisis hasil penelitian yang menghasilkan data deskriptif analitis, yaitu data yang dinyatakan oleh responden sacara tertulis atau lisan serta juga tingkah laku yang nyata, yang diteliti dan dipelajari sebagai sesuatu yang utuh. Pelaksanaan rehabilitasi belum dilaksanakan secara optimal oleh penegak hukum di wilayah hukum Kejaksaan Negeri Mejayan Kabupaten Madiun terhadap pelaku penyalahguna narkotika. Upaya-upaya terhadap pelaksanaan rehabilitasi penyalahguna narkotika, aparat penegak hukum di wilayah hukum Kejaksaan Negeri Mejayan Kabupaten Madiun dibantu oleh Pemerintah Kabupaten Madiun dalam proses awal penegakan hukum terhadap penyalahguna narkotika sedini mungkin dilakukannya Assesmen Terpadu. Kata kunci : Rehabilitasi Narkotika, Penanganan Perkara Pidana
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