Testing systems of identical components

We consider the problem of testing sequentially the components of a multi-component reliability system in order to figure out the state of the system via costly tests. In particular, systems with identical components are considered. The notion of lexicographically large binary decision trees is introduced and a heuristic algorithm based on that notion is proposed. The performance of the heuristic algorithm is demonstrated by computational results, for various classes of functions. In particular, in all 200 random cases where the underlying function is a threshold function, the proposed heuristic produces optimal solutions

On the Ballot for Nov. 2, 2021: the Constitutional Amendment on Redistricting

On November 2, 2021, New York State voters will be asked to approve a constitutional amendment revising the redistricting process to be based on the 2020 census. If the constitutional amendment is approved, the changes will take effect on January 1, 2022. This amendment is necessary to address delays in the census created by the pandemic and to accommodate New York State’s change from a September primary to an earlier June primary for both federal and state elections. These changes compressed the time needed to complete the redistricting. Without these changes, it is possible that the new districts will not be ready in time for the political process to function

Determining the Solution Space of Vertex-Cover by Interactions and Backbones

To solve the combinatorial optimization problems especially the minimal Vertex-cover problem with high efficiency, is a significant task in theoretical computer science and many other subjects. Aiming at detecting the solution space of Vertex-cover, a new structure named interaction between nodes is defined and discovered for random graph, which results in the emergence of the frustration and long-range correlation phenomenon. Based on the backbones and interactions with a node adding process, we propose an Interaction and Backbone Evolution Algorithm to achieve the reduced solution graph, which has a direct correspondence to the solution space of Vertex-cover. By this algorithm, the whole solution space can be obtained strictly when there is no leaf-removal core on the graph and the odd cycles of unfrozen nodes bring great obstacles to its efficiency. Besides, this algorithm possesses favorable exactness and has good performance on random instances even with high average degrees. The interaction with the algorithm provides a new viewpoint to solve Vertex-cover, which will have a wide range of applications to different types of graphs, better usage of which can lower the computational complexity for solving Vertex-cover

The Marine Viromes of Four Oceanic Regions

Viruses are the most common biological entities in the marine environment. There has not been a global survey of these viruses, and consequently, it is not known what types of viruses are in Earth's oceans or how they are distributed. Metagenomic analyses of 184 viral assemblages collected over a decade and representing 68 sites in four major oceanic regions showed that most of the viral sequences were not similar to those in the current databases. There was a distinct “marine-ness” quality to the viral assemblages. Global diversity was very high, presumably several hundred thousand of species, and regional richness varied on a North-South latitudinal gradient. The marine regions had different assemblages of viruses. Cyanophages and a newly discovered clade of single-stranded DNA phages dominated the Sargasso Sea sample, whereas prophage-like sequences were most common in the Arctic. However most viral species were found to be widespread. With a majority of shared species between oceanic regions, most of the differences between viral assemblages seemed to be explained by variation in the occurrence of the most common viral species and not by exclusion of different viral genomes. These results support the idea that viruses are widely dispersed and that local environmental conditions enrich for certain viral types through selective pressure

Occupancy Modeling, Maximum Contig Size Probabilities and Designing Metagenomics Experiments

Mathematical aspects of coverage and gaps in genome assembly have received substantial attention by bioinformaticians. Typical problems under consideration suppose that reads can be experimentally obtained from a single genome and that the number of reads will be set to cover a large percentage of that genome at a desired depth. In metagenomics experiments genomes from multiple species are simultaneously analyzed and obtaining large numbers of reads per genome is unlikely. We propose the probability of obtaining at least one contig of a desired minimum size from each novel genome in the pool without restriction based on depth of coverage as a metric for metagenomic experimental design. We derive an approximation to the distribution of maximum contig size for single genome assemblies using relatively few reads. This approximation is verified in simulation studies and applied to a number of different metagenomic experimental design problems, ranging in difficulty from detecting a single novel genome in a pool of known species to detecting each of a random number of novel genomes collectively sized and with abundances corresponding to given distributions in a single pool

Scalable data management in distributed information systems

[EN] In the era of cloud computing and huge information systems, distributed applications should manage dynamic workloads; i.e., the amount of client requests per time unit may vary frequently and servers should rapidly adapt their computing efforts to those workloads. Cloud systems provide a solid basis for this kind of applications but most of the traditional relational database systems are unprepared to scale up with this kind of distributed systems. This paper surveys different techniques being used in modern SQL, NoSQL and NewSQL systems in order to increase the scalability and adaptability in the management of persistent data. © 2011 Springer-Verlag.This work has been supported by EU FEDER and Spanish MICINN under research grants TIN2009-14460-C03-01 and TIN2010-17193Pallardó Lozoya, MR.; Esparza Peidro, J.; García Escriva, JR.; Decker, H.; Muñoz Escoí, FD. (2011). Scalable data management in distributed information systems. Lecture Notes in Computer Science. 7046:208-217. https://doi.org/10.1007/978-3-642-25126-9_31S2082177046Helland, P.: Life beyond distributed transactions: an apostate’s opinion. In: 3rd Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 132–141 (2007)Finkelstein, S., Jacobs, D., Brendle, R.: Principles for inconsistency. In: 4th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA (2009)Chang, F., Dean, J., Ghemawat, S., Hsieh, W.C., Wallach, D.A., Burrows, M., Chandra, T., Fikes, A., Gruber, R.: Bigtable: A distributed storage system for structured data. In: 7th Symp. on Operat. Syst. Design and Implem. (OSDI), pp. 205–218. USENIX Assoc., Seattle (2006)Cooper, B.F., Baldeschwieler, E., Fonseca, R., Kistler, J.J., Narayan, P.P.S., Neerdaels, C., Negrin, T., Ramakrishnan, R., Silberstein, A., Srivastava, U., Stata, R.: Building a cloud for Yahoo! IEEE Data Eng. Bull. 32, 36–43 (2009)DeCandia, G., Hastorun, D., Jampani, M., Kakulapati, G., Lakshman, A., Pilchin, A., Sivasubramanian, S., Vosshall, P., Vogels, W.: Dynamo: Amazon’s highly available key-value store. In: 21st ACM Symp. on Operat. Syst. Princ. (SOSP), Stevenson, Washington, USA, pp. 205–220 (2007)Stonebraker, M., Madden, S., Abadi, D.J., Harizopoulos, S., Hachem, N., Helland, P.: The end of an architectural era (it’s time for a complete rewrite). In: 33rd Intnl. Conf. on Very Large Data Bases (VLDB), pp. 1150–1160. ACM Press, Vienna (2007)Lomet, D.B., Fekete, A., Weikum, G., Zwilling, M.J.: Unbundling transaction services in the cloud. In: 4th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA (2009)Campbell, D.G., Kakivaya, G., Ellis, N.: Extreme scale with full SQL language support in Microsoft SQL Azure. In: Intnl. Conf. on Mngmnt. of Data (SIGMOD), pp. 1021–1024. ACM, New York (2010)Levandoski, J.J., Lomet, D., Mokbel, M.F., Zhao, K.K.: Deuteronomy: Transaction support for cloud data. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 123–133 (2011)Helland, P., Campbell, D.: Building on quicksand. In: 4th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA (2009)Muñoz-Escoí, F.D., García-Escrivá, J.R., Pallardó-Lozoya, M.R., Esparza-Peidro, J.: Managing scalable persistent data. Technical Report ITI-SIDI-2011/003, Instituto Tecnológico de Informática, Universitat Politècnica de València, Spain (2011)Agrawal, D., El Abbadi, A., Antony, S., Das, S.: Data management challenges in cloud computing infrastructures. In: 6th Intnl. Wshop. on Databases in Networked Information Systems (DNIS), Aizu-Wakamatsu, Japan, pp. 1–10 (2010)Stonebraker, M.: The case for shared nothing. IEEE Database Eng. Bull. 9, 4–9 (1986)Alonso, G., Kossmann, D., Roscoe, T.: SwissBox: An architecture for data processing appliances. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 32–37 (2011)Baker, J., Bond, C., Corbett, J.C., Furman, J.J., Khorlin, A., Larson, J., Léon, J.M., Li, Y., Lloyd, A., Yushprakh, V.: Megastore: Providing scalable, highly available storage for interactive services. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 223–234 (2011)Curino, C., Jones, E.P.C., Popa, R.A., Malviya, N., Wu, E., Madden, S., Balakrishnan, H., Zeldovich, N.: Relational cloud: A database-as-a-service for the cloud. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 235–240 (2011)Das, S., Agrawal, D., El Abbadi, A.: ElasTraS: An elastic transactional data store in the cloud. CoRR abs/1008.3751 (2010)Vogels, W.: Eventually consistent. Commun. ACM 52, 40–44 (2009)Breitbart, Y., Korth, H.F.: Replication and consistency: being lazy helps sometimes. In: 16th ACM Symp. on Princ. of Database Syst., PODS 1997, pp. 173–184. ACM, New York (1997)Brantner, M., Florescu, D., Graf, D.A., Kossmann, D., Kraska, T.: Building a database on S3. In: Intnl. Conf. on Mngmnt. of Data (SIGMOD), pp. 251–264. ACM Press, Vancouver (2008)Lakshman, A., Malik, P.: Cassandra: a decentralized structured storage system. Operating Systems Review 44, 35–40 (2010)Burrows, M.: The Chubby lock service for loosely-coupled distributed systems. In: 7th Symp. on Operat. Syst. Design and Implem. (OSDI), pp. 335–350. USENIX Assoc., Seattle (2006)Junqueira, F.P., Reed, B.: The life and times of a ZooKeeper. In: 28th Annual ACM Symp. on Princ. of Distrib. Comp. (PODC), p. 4. ACM Press, Calgary (2009)MacCormick, J., Murphy, N., Najork, M., Thekkath, C.A., Zhou, L.: Boxwood: Abstractions as the foundation for storage infrastructure. In: 6th Simp. on Operat. Syst. Design and Impl. (OSDI), pp. 105–120. USENIX Assoc., San Francisco (2004)Stonebraker, M., Cattell, R.: Ten rules for scalable performance in ”simple operation” datastores. Commun. ACM 54, 72–80 (2011)Amazon Web Services LLC: Amazon SimpleDB (2011), http://aws.amazon.com/simpledb/Lamport, L.: The part-time parliament. ACM Trans. Comput. Syst. 16, 133–169 (1998)Bernstein, P.A., Reid, C.W., Das, S.: Hyder - a transactional record manager for shared flash. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 9–20 (2011)Bonnet, P., Bouganim, L.: Flash device support for database management. In: 5th Biennial Conf. on Innov. Data Syst. Research (CIDR), Asilomar, CA, USA, pp. 1–8 (2011)Microsoft Corp.: Windows Azure: Microsoft’s cloud services platform (2011), http://www.microsoft.com/windowsazure/VoltDB, Inc.: VoltDB technical overview: Next generation open-source SQL database with ACID for fast-scaling OLTP applications (2010), Downloadable from: http://voltdb.com/_pdf/VoltDBTechnicalOverviewWhitePaper.pd

Stability analysis on the finite-temperature replica-symmetric and first-step replica-symmetry-broken cavity solutions of the random vertex cover problem

The vertex-cover problem is a prototypical hard combinatorial optimization problem. It was studied in recent years by physicists using the cavity method of statistical mechanics. In this paper, the stability of the finite-temperature replica-symmetric (RS) and the first-step replica-symmetry-broken (1RSB) cavity solutions of the vertex cover problem on random regular graphs of finite vertex-degree $K$ are analyzed by population dynamics simulations. We found that (1) the lowest temperature for the RS solution to be stable, $T_{RS}(K)$, is not a monotonic function of $K$, and (2) at relatively large connectivity $K$ and temperature $T$ slightly below the dynamic transition temperature $T_d(K)$, the 1RSB solutions with small but non-negative complexity values are stable. Similar results are obtained on random Poissonian graphs.Comment: 15 pages, 9 figure