A Maude specification of the Kademlia distributed hash table: centralized version

Kademlia is the most popular peer-to-peer distributed hash table (DHT) currently in use. It offers a number of desirable features that result from the use of a notion of distance between objects based on the bitwise exclusive or of n-bit quantities that represent both nodes and files. Nodes keep information about files close or near to them in the key space and the search algorithm is based on looking for the closest node to the file key. The structure of the routing table defined in each peer guarantees that the lookup algorithm takes no longer than logn steps. We have developed a formal specification of a P2P network that uses the Kademlia DHT in the Maude language. We use sockets to connect different Maude instances and create a P2P network where the Kademlia protocol can be used, hence providing an implementation of the protocol which is correct by design. Then, we show how to abstract this system in order to analyze it using Real-Time Maude. The model is fully parameterized regarding the time taken by the different actions to facilitate the analysis of various scenarios. Finally, we use time-bounded model-checking and exhaustive search to prove properties of the protocol over different scenarios. This report focuses on the implementation details of the centralized specification

A Survey of Algorithmic Debugging

"© ACM, 2017. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Computing Surveys, {50, 4, 2017} https://dl.acm.org/doi/10.1145/3106740"[EN] Algorithmic debugging is a technique proposed in 1982 by E. Y. Shapiro in the context of logic programming. This survey shows how the initial ideas have been developed to become a widespread debugging schema ftting many diferent programming paradigms and with applications out of the program debugging feld. We describe the general framework and the main issues related to the implementations in diferent programming paradigms and discuss several proposed improvements and optimizations. We also review the main algorithmic debugger tools that have been implemented so far and compare their features. From this comparison, we elaborate a summary of desirable characteristics that should be considered when implementing future algorithmic debuggers.This work has been partially supported by the EU (FEDER) and the Spanish Ministerio de Economia y Competitividad under grant TIN2013-44742-C4-1-R, TIN2016-76843-C4-1-R, StrongSoft (TIN2012-39391-C04-04), and TRACES (TIN2015-67522-C3-3-R) by the Generalitat Valenciana under grant PROMETEO-II/2015/013 (SmartLogic) and by the Comunidad de Madrid project N-Greens Software-CM (S2013/ICE-2731).Caballero, R.; Riesco, A.; Silva, J. (2017). A Survey of Algorithmic Debugging. ACM Computing Surveys. 50(4):1-35. https://doi.org/10.1145/3106740S135504Abramson, D., Foster, I., Michalakes, J., & Sosič, R. (1996). Relative debugging. Communications of the ACM, 39(11), 69-77. doi:10.1145/240455.240475K. R. Apt H. A. Blair and A. Walker. 1988. Towards a theory of declarative knowledge. In Foundations of Deductive Databases and Logic Programming J. Minker (Ed.). Morgan Kaufmann Publishers Inc. San Francisco CA 89--148. 10.1016/B978-0-934613-40-8.50006-3 K. R. Apt H. A. Blair and A. Walker. 1988. Towards a theory of declarative knowledge. In Foundations of Deductive Databases and Logic Programming J. Minker (Ed.). Morgan Kaufmann Publishers Inc. San Francisco CA 89--148. 10.1016/B978-0-934613-40-8.50006-3Arora, T., Ramakrishnan, R., Roth, W. G., Seshadri, P., & Srivastava, D. (1993). Explaining program execution in deductive systems. Lecture Notes in Computer Science, 101-119. doi:10.1007/3-540-57530-8_7E. Av-Ron. 1984. Top-Down Diagnosis of Prolog Programs. Ph.D. Dissertation. Weizmann Institute. E. Av-Ron. 1984. Top-Down Diagnosis of Prolog Programs. Ph.D. Dissertation. Weizmann Institute.A. Beaulieu. 2005. Learning SQL. O’Reilly Farnham UK. A. Beaulieu. 2005. Learning SQL. O’Reilly Farnham UK.D. Binks. 1995. Declarative Debugging in Gödel. Ph.D. Dissertation. University of Bristol. D. Binks. 1995. Declarative Debugging in Gödel. Ph.D. Dissertation. University of Bristol.B. Braßel and H. Siegel. 2008. Debugging Lazy Functional Programs by Asking the Oracle. Springer-Verlag Berlin 183--200. DOI:http://dx.doi.org/10.1007/978-3-540-85373-2_11 10.1007/978-3-540-85373-2_11 B. Braßel and H. Siegel. 2008. Debugging Lazy Functional Programs by Asking the Oracle. Springer-Verlag Berlin 183--200. DOI:http://dx.doi.org/10.1007/978-3-540-85373-2_11 10.1007/978-3-540-85373-2_11Caballero, R. (2005). A declarative debugger of incorrect answers for constraint functional-logic programs. Proceedings of the 2005 ACM SIGPLAN workshop on Curry and functional logic programming - WCFLP ’05. doi:10.1145/1085099.1085102Caballero, R., García-Ruiz, Y., & Sáenz-Pérez, F. (2012). Declarative Debugging of Wrong and Missing Answers for SQL Views. Lecture Notes in Computer Science, 73-87. doi:10.1007/978-3-642-29822-6_9Caballero, R., García-Ruiz, Y., & Sáenz-Pérez, F. (2015). Debugging of wrong and missing answers for datalog programs with constraint handling rules. Proceedings of the 17th International Symposium on Principles and Practice of Declarative Programming - PPDP ’15. doi:10.1145/2790449.2790522Caballero, R., Martin-Martin, E., Riesco, A., & Tamarit, S. (2015). A zoom-declarative debugger for sequential Erlang programs. Science of Computer Programming, 110, 104-118. doi:10.1016/j.scico.2015.06.011Caballero, R., & Rodríguez-Artalejo, M. (2002). A Declarative Debugging System for Lazy Functional Logic Programs. Electronic Notes in Theoretical Computer Science, 64, 113-175. doi:10.1016/s1571-0661(04)80349-9Ceri, S., Gottlob, G., & Tanca, L. (1989). What you always wanted to know about Datalog (and never dared to ask). IEEE Transactions on Knowledge and Data Engineering, 1(1), 146-166. doi:10.1109/69.43410Chen, M., Mao, S., & Liu, Y. (2014). Big Data: A Survey. Mobile Networks and Applications, 19(2), 171-209. doi:10.1007/s11036-013-0489-0Chitil, O., & Davie, T. (2008). Comprehending finite maps for algorithmic debugging of higher-order functional programs. Proceedings of the 10th international ACM SIGPLAN symposium on Principles and practice of declarative programming - PPDP ’08. doi:10.1145/1389449.1389475Chitil, O., Faddegon, M., & Runciman, C. (2016). A Lightweight Hat. Proceedings of the 28th Symposium on the Implementation and Application of Functional Programming Languages - IFL 2016. doi:10.1145/3064899.3064904O. Chitil C. Runciman and M. Wallace. 2001. Freja Hat and Hood—A Comparative Evaluation of Three Systems for Tracing and Debugging Lazy Functional Programs. Springer Berlin 176--193. O. Chitil C. Runciman and M. Wallace. 2001. Freja Hat and Hood—A Comparative Evaluation of Three Systems for Tracing and Debugging Lazy Functional Programs. Springer Berlin 176--193.O. Chitil C. Runciman and Malcolm Wallace. 2003. Transforming Haskell for Tracing. Springer-Verlag Berlin 165--181. DOI:http://dx.doi.org/10.1007/3-540-44854-3_11 10.1007/3-540-44854-3_11 O. Chitil C. Runciman and Malcolm Wallace. 2003. Transforming Haskell for Tracing. Springer-Verlag Berlin 165--181. DOI:http://dx.doi.org/10.1007/3-540-44854-3_11 10.1007/3-540-44854-3_11Minh Ngoc Dinh, Abramson, D., & Chao Jin. (2014). Scalable Relative Debugging. IEEE Transactions on Parallel and Distributed Systems, 25(3), 740-749. doi:10.1109/tpds.2013.86Faddegon, M., & Chitil, O. (2015). Algorithmic debugging of real-world haskell programs: deriving dependencies from the cost centre stack. ACM SIGPLAN Notices, 50(6), 33-42. doi:10.1145/2813885.2737985Faddegon, M., & Chitil, O. (2016). Lightweight computation tree tracing for lazy functional languages. Proceedings of the 37th ACM SIGPLAN Conference on Programming Language Design and Implementation - PLDI 2016. doi:10.1145/2908080.2908104Ferrand, G. (1987). Error diagnosis in logic programming an adaptation of E.Y. Shapiro’s method. The Journal of Logic Programming, 4(3), 177-198. doi:10.1016/0743-1066(87)90001-xFritzson, P., Shahmehri, N., Kamkar, M., & Gyimothy, T. (1992). Generalized algorithmic debugging and testing. ACM Letters on Programming Languages and Systems, 1(4), 303-322. doi:10.1145/161494.161498Fromherz, M. P. J. (s. f.). Towards declarative debugging of concurrent constraint programs. Lecture Notes in Computer Science, 88-100. doi:10.1007/bfb0019403Harman, M., & Hierons, R. (2001). An overview of program slicing. Software Focus, 2(3), 85-92. doi:10.1002/swf.41F. Henderson T. Conway Z. Somogyi D. Jeffery P. Schachte S. Taylor C. Speirs T. Dowd R. Becket M. Brown and P. Wang. 2014. The Mercury Language Reference Manual (Version 14.01.1). The University of Melbourne. F. Henderson T. Conway Z. Somogyi D. Jeffery P. Schachte S. Taylor C. Speirs T. Dowd R. Becket M. Brown and P. Wang. 2014. The Mercury Language Reference Manual (Version 14.01.1). The University of Melbourne.C. Hermanns and H. Kuchen. 2013. Hybrid Debugging of Java Programs. Springer-Verlag Berlin 91--107. DOI:http://dx.doi.org/10.1007/978-3-642-36177-7_6 10.1007/978-3-642-36177-7_6 C. Hermanns and H. Kuchen. 2013. Hybrid Debugging of Java Programs. Springer-Verlag Berlin 91--107. DOI:http://dx.doi.org/10.1007/978-3-642-36177-7_6 10.1007/978-3-642-36177-7_6Hirunkitti, V., & Hogger, C. J. (s. f.). A generalised query minimisation for program debugging. Lecture Notes in Computer Science, 153-170. doi:10.1007/bfb0019407Hughes, J. (2010). Software Testing with QuickCheck. Lecture Notes in Computer Science, 183-223. doi:10.1007/978-3-642-17685-2_6G. Hutton. 2016. Programming in Haskell. Cambridge University Press Cambridge UK. G. Hutton. 2016. Programming in Haskell. Cambridge University Press Cambridge UK.Insa, D., & Silva, J. (2010). An algorithmic debugger for Java. 2010 IEEE International Conference on Software Maintenance. doi:10.1109/icsm.2010.5609661Insa, D., & Silva, J. (2011). Optimal Divide and Query. Lecture Notes in Computer Science, 224-238. doi:10.1007/978-3-642-24769-9_17Insa, D., & Silva, J. (2011). An optimal strategy for algorithmic debugging. 2011 26th IEEE/ACM International Conference on Automated Software Engineering (ASE 2011). doi:10.1109/ase.2011.6100055D. Insa and J. Silva. 2011c. Scaling Up Algorithmic Debugging with Virtual Execution Trees. Springer-Verlag Berlin 149--163. DOI:http://dx.doi.org/10.1007/978-3-642-20551-4_10 10.1007/978-3-642-20551-4_10 D. Insa and J. Silva. 2011c. Scaling Up Algorithmic Debugging with Virtual Execution Trees. Springer-Verlag Berlin 149--163. DOI:http://dx.doi.org/10.1007/978-3-642-20551-4_10 10.1007/978-3-642-20551-4_10D. Insa and J. Silva. 2015a. Automatic transformation of iterative loops into recursive methods. Information 8 Software Technology 58 (2015) 95--109. DOI:http://dx.doi.org/10.1016/j.infsof.2014.10.001 10.1016/j.infsof.2014.10.001 D. Insa and J. Silva. 2015a. Automatic transformation of iterative loops into recursive methods. Information 8 Software Technology 58 (2015) 95--109. DOI:http://dx.doi.org/10.1016/j.infsof.2014.10.001 10.1016/j.infsof.2014.10.001Insa, D., & Silva, J. (2015). A Generalized Model for Algorithmic Debugging. Lecture Notes in Computer Science, 261-276. doi:10.1007/978-3-319-27436-2_16Insa, D., Silva, J., & Riesco, A. (2013). Speeding Up Algorithmic Debugging Using Balanced Execution Trees. Lecture Notes in Computer Science, 133-151. doi:10.1007/978-3-642-38916-0_8Insa, D., Silva, J., & Tomás, C. (2013). Enhancing Declarative Debugging with Loop Expansion and Tree Compression. Lecture Notes in Computer Science, 71-88. doi:10.1007/978-3-642-38197-3_6K. Jensen and N. Wirth. 1974. PASCAL User Manual and Report. Springer-Verlag Berlin. 10.1007/978-3-662-21554-8 K. Jensen and N. Wirth. 1974. PASCAL User Manual and Report. Springer-Verlag Berlin. 10.1007/978-3-662-21554-8Jia, Y., & Harman, M. (2011). An Analysis and Survey of the Development of Mutation Testing. IEEE Transactions on Software Engineering, 37(5), 649-678. doi:10.1109/tse.2010.62Kamkar, M., Shahmehri, N., & Fritzson, P. (s. f.). Bug localization by algorithmic debugging and program slicing. Lecture Notes in Computer Science, 60-74. doi:10.1007/bfb0024176S. Köhler B. Ludäscher and Y. Smaragdakis. 2012. Declarative Datalog Debugging for Mere Mortals. Springer-Verlag Berlin 111--122. S. Köhler B. Ludäscher and Y. Smaragdakis. 2012. Declarative Datalog Debugging for Mere Mortals. Springer-Verlag Berlin 111--122.Kouh, H.-J., & Yoo, W.-H. (2003). The Efficient Debugging System for Locating Logical Errors in Java Programs. Lecture Notes in Computer Science, 684-693. doi:10.1007/3-540-44839-x_72Benzmüller, C., & Miller, D. (2014). Automation of Higher-Order Logic. Handbook of the History of Logic, 215-254. doi:10.1016/b978-0-444-51624-4.50005-8Kowalski, R., & Kuehner, D. (1971). Linear resolution with selection function. Artificial Intelligence, 2(3-4), 227-260. doi:10.1016/0004-3702(71)90012-9K. Kuchcinski W. Drabent and J. Maluszynski. 1993. Automatic Diagnosis of VLSI Digital Circuits Using Algorithmic Debugging. Springer-Verlag Berlin 350--367. DOI:http://dx.doi.org/10.1007/BFb0019419 10.1007/BFb0019419 K. Kuchcinski W. Drabent and J. Maluszynski. 1993. Automatic Diagnosis of VLSI Digital Circuits Using Algorithmic Debugging. Springer-Verlag Berlin 350--367. DOI:http://dx.doi.org/10.1007/BFb0019419 10.1007/BFb0019419S. Liang. 1999. Java Native Interface: Programmer’s Guide and Reference (1st ed.). Addison-Wesley Longman Publishing Co. Inc. Boston MA. S. Liang. 1999. Java Native Interface: Programmer’s Guide and Reference (1st ed.). Addison-Wesley Longman Publishing Co. Inc. Boston MA.Lloyd, J. W. (1987). Declarative error diagnosis. New Generation Computing, 5(2), 133-154. doi:10.1007/bf03037396J. W. Lloyd. 1987b. Foundations of Logic Programming (2nd ed.). Springer-Verlag Berlin. 10.1007/978-3-642-83189-8 J. W. Lloyd. 1987b. Foundations of Logic Programming (2nd ed.). Springer-Verlag Berlin. 10.1007/978-3-642-83189-8W. Lux. 2006. Münster Curry User’s guide (Release 0.9.10 of May 10 2006). Retrieved from http://danae.uni-muenster.de/∼lux/curry/user.pdf. W. Lux. 2006. Münster Curry User’s guide (Release 0.9.10 of May 10 2006). Retrieved from http://danae.uni-muenster.de/∼lux/curry/user.pdf.Lux, W. (2008). Declarative Debugging Meets the World. Electronic Notes in Theoretical Computer Science, 216, 65-77. doi:10.1016/j.entcs.2008.06.034I. MacLarty. 2005. Practical Declarative Debugging of Mercury Programs. Ph.D. Dissertation. Department of Computer Science and Software Engineering The University of Melbourne. I. MacLarty. 2005. Practical Declarative Debugging of Mercury Programs. Ph.D. Dissertation. Department of Computer Science and Software Engineering The University of Melbourne.Naganuma, J., Ogura, T., & Hoshino, T. (s. f.). High-level design validation using algorithmic debugging. Proceedings of European Design and Test Conference EDAC-ETC-EUROASIC. doi:10.1109/edtc.1994.326833Naish, L. (1992). Declarative diagnosis of missing answers. New Generation Computing, 10(3), 255-285. doi:10.1007/bf03037939H. Nilsson. 1998. Declarative Debugging for Lazy Functional Languages. Ph.D. Dissertation. Linköping Sweden. H. Nilsson. 1998. Declarative Debugging for Lazy Functional Languages. Ph.D. Dissertation. Linköping Sweden.NILSSON, H. (2001). How to look busy while being as lazy as ever: the Implementation of a lazy functional debugger. Journal of Functional Programming, 11(6), 629-671. doi:10.1017/s095679680100418xNilsson, H., & Fritzson, P. (s. f.). Algorithmic debugging for lazy functional languages. Lecture Notes in Computer Science, 385-399. doi:10.1007/3-540-55844-6_149Nilsson, H., & Fritzson, P. (1994). Algorithmic debugging for lazy functional languages. Journal of Functional Programming, 4(3), 337-369. doi:10.1017/s095679680000109xNilsson, H., & Sparud, J. (1997). Automated Software Engineering, 4(2), 121-150. doi:10.1023/a:1008681016679Ostrand, T. J., & Balcer, M. J. (1988). The category-partition method for specifying and generating fuctional tests. Communications of the ACM, 31(6), 676-686. doi:10.1145/62959.62964Pereira, L. M. (1986). Rational debugging in logic programming. Third International Conference on Logic Programming, 203-210. doi:10.1007/3-540-16492-8_76B. Pope. 2006. A Declarative Debugger for Haskell. Ph.D. Dissertation. The University of Melbourne Australia. B. Pope. 2006. A Declarative Debugger for Haskell. Ph.D. Dissertation. The University of Melbourne Australia.Ramakrishnan, R., & Ullman, J. D. (1995). A survey of deductive database systems. The Journal of Logic Programming, 23(2), 125-149. doi:10.1016/0743-1066(94)00039-9Riesco, A., Verdejo, A., Martí-Oliet, N., & Caballero, R. (2012). Declarative debugging of rewriting logic specifications. The Journal of Logic and Algebraic Programming, 81(7-8), 851-897. doi:10.1016/j.jlap.2011.06.004DeRose, L., Gontarek, A., Vose, A., Moench, R., Abramson, D., Dinh, M. N., & Jin, C. (2015). Relative debugging for a highly parallel hybrid computer system. Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis on - SC ’15. doi:10.1145/2807591.2807605Runeson, P. (2006). A survey of unit testing practices. IEEE Software, 23(4), 22-29. doi:10.1109/ms.2006.91Russo, F., & Sancassani, M. (1992). A declarative debugging environment for DATALOG. Lecture Notes in Computer Science, 433-441. doi:10.1007/3-540-55460-2_32E. Y. Shapiro. 1982a. Algorithmic Program Debugging. MIT Press Cambridge MA. E. Y. Shapiro. 1982a. Algorithmic Program Debugging. MIT Press Cambridge MA.Shapiro, E. Y. (1982). Algorithmic program diagnosis. Proceedings of the 9th ACM SIGPLAN-SIGACT symposium on Principles of programming languages - POPL ’82. doi:10.1145/582153.582185Shmueli, O., & Tsur, S. (1991). Logical diagnosis ofLDL programs. New Generation Computing, 9(3-4), 277-303. doi:10.1007/bf03037166Silva, J. (s. f.). A Comparative Study of Algorithmic Debugging Strategies. Lecture Notes in Computer Science, 143-159. doi:10.1007/978-3-540-71410-1_11Silva, J. (2011). A survey on algorithmic debugging strategies. Advances in Engineering Software, 42(11), 976-991. doi:10.1016/j.advengsoft.2011.05.024Silva, J., & Chitil, O. (2006). Combining algorithmic debugging and program slicing. Proceedings of the 8th ACM SIGPLAN symposium on Principles and practice of declarative programming - PPDP ’06. doi:10.1145/1140335.1140355J. A. Silva E. R. Faria R. C. Barros E. R. Hruschka A. C. P. L. F. de Carvalho and J. Gama. 2013. Data stream clustering: A survey. Comput. Surv. 46 1 Article 13 (July 2013) 31 pages.DOI:http://dx.doi.org/10.1145/2522968.2522981 10.1145/2522968.2522981 J. A. Silva E. R. Faria R. C. Barros E. R. Hruschka A. C. P. L. F. de Carvalho and J. Gama. 2013. Data stream clustering: A survey. Comput. Surv. 46 1 Article 13 (July 2013) 31 pages.DOI:http://dx.doi.org/10.1145/2522968.2522981 10.1145/2522968.2522981SOSIČ, R., & ABRAMSON, D. (1997). Guard: A Relative Debugger. Software: Practice and Experience, 27(2), 185-206. doi:10.1002/(sici)1097-024x(199702)27:23.0.co;2-dL. Sterling and E. Shapiro. 1986. The Art of Prolog: Advanced Programming Techniques. The MIT Press Cambridge MA. L. Sterling and E. Shapiro. 1986. The Art of Prolog: Advanced Programming Techniques. The MIT Press Cambridge MA.P. Kambam Sugavanam. 2013. Debugging Framework for Attribute Grammars. Ph.D. Dissertation. University of Minnesota. P. Kambam Sugavanam. 2013. Debugging Framework for Attribute Grammars. Ph.D. Dissertation. University of Minnesota.Tamarit, S., Riesco, A., Martin-Martin, E., & Caballero, R. (2016). Debugging Meets Testing in Erlang. Lecture Notes in Computer Science, 171-180. doi:10.1007/978-3-319-41135-4_10A. Tessier and G. Ferrand. 2000. Declarative diagnosis in the CLP scheme. In Analysis and Visualization Tools for Constraint Programming: Constraint Debugging Pierre Deransart Manuel V. Hermenegildo and Jan Maluszynski (Eds.). Springer-Verlag Berlin 151--174. 10.1007/10722311_6 A. Tessier and G. Ferrand. 2000. Declarative diagnosis in the CLP scheme. In Analysis and Visualization Tools for Constraint Programming: Constraint Debugging Pierre Deransart Manuel V. Hermenegildo and Jan Maluszynski (Eds.). Springer-Verlag Berlin 151--174. 10.1007/10722311_6Zinn, C. (2013). Algorithmic Debugging for Intelligent Tutoring: How to Use Multiple Models and Improve Diagnosis. Lecture Notes in Computer Science, 272-283. doi:10.1007/978-3-642-40942-4_24Zinn, C. (2014). Algorithmic Debugging and Literate Programming to Generate Feedback in Intelligent Tutoring Systems. KI 2014: Advances in Artificial Intelligence, 37-48. doi:10.1007/978-3-319-11206-0_

Speeding Up Algorithmic Debugging Using Balanced Execution Trees

Algorithmic debugging is a debugging technique that uses a data structure representing all computations performed during the execution of a program. This data structure is the so-called Execution Tree and it strongly influences the performance of the technique. In this work we present a transformation that automatically improves the structure of the execution trees by collapsing and projecting some strategic nodes. This improvement in the structure implies a better behavior and performance of the standard algorithms that traverse it. We prove that the transformation is sound in the sense that all the bugs found after the transformation are real bugs; and if at least one bug is detectable before the transformation, then at least one bug will also be detectable after the transformation. We have implemented the technique and performed several experiments with real applications. The experimental results confirm the usefulness of the technique.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovación under grants TIN2008-06622-C03-02 and TIN2012-39391-004-04, by the Generalitat Valenciana under grant ACOMP/2009/017, and by the Comunidad de Madrid under grant S2009/TIC-1465. David Insa has been partially supported by the Spanish Ministerio de Educación under grant AP2010-4415.Silva, J.; Insa Cabrera, D.; Riesco, A. (2013). Speeding Up Algorithmic Debugging Using Balanced Execution Trees. En Tests and Proofs. Springer. 133-151. https://doi.org/10.1007/978-3-642-38916-0_8S133151Binks, D.: Declarative Debugging in Gödel. PhD thesis, University of Bristol (1995)Caballero, R.: A Declarative Debugger of Incorrect Answers for Constraint Functional-Logic Programs. In: Proc. of the 2005 ACM SIGPLAN Workshop on Curry and Functional Logic Programming, WCFLP 2005, pp. 8–13. ACM Press (2005)Caballero, R., Hermanns, C., Kuchen, H.: Algorithmic debugging of Java programs. In: López-Fraguas, F.J. (ed.) Proc. of the 15th Workshop on Functional and (Constraint) Logic Programming, WFLP 2006, Madrid, Spain. ENTCS, vol. 177, pp. 75–89. Elsevier (2007)Calejo, M.: A Framework for Declarative Prolog Debugging. PhD thesis, New University of Lisbon (1992)Davie, T., Chitil, O.: Hat-delta: One Right Does Make a Wrong. In: Seventh Symposium on Trends in Functional Programming, TFP 2006 (April 2006)Hirunkitti, V., Hogger, C.J.: A Generalised Query Minimisation for Program Debugging. In: Fritzson, P.A. (ed.) AADEBUG 1993. LNCS, vol. 749, pp. 153–170. Springer, Heidelberg (1993)Insa, D., Silva, J.: Scaling up algorithmic debugging with virtual execution trees. In: Alpuente, M. (ed.) LOPSTR 2010. LNCS, vol. 6564, pp. 149–163. Springer, Heidelberg (2011)Insa, D., Silva, J., Riesco, A.: Speeding up algorithmic debugging using balanced execution trees—detailed results. Technical Report 04/13, Departamento de Sistemas Informáticos y Computación (April 2013)Kokai, G., Nilson, J., Niss, C.: GIDTS: A Graphical Programming Environment for Prolog. In: Workshop on Program Analysis For Software Tools and Engineering, PASTE 1999, pp. 95–104. ACM Press (1999)MacLarty, I.: Practical Declarative Debugging of Mercury Programs. PhD thesis, Department of Computer Science and Software Engineering, University of Melbourne (2005)Maeji, M., Kanamori, T.: Top-Down Zooming Diagnosis of Logic Programs. Technical Report TR-290, Japan (1987)Nilsson, H.: Declarative Debugging for Lazy Functional Languages. PhD thesis, Linköping, Sweden (May 1998)Nilsson, H., Fritzson, P.: Algorithmic Debugging for Lazy Functional Languages. Journal of Functional Programming 4(3), 337–370 (1994)Shapiro, E.Y.: Algorithmic Program Debugging. MIT Press (1982)Silva, J.: A Survey on Algorithmic Debugging Strategies. Advances in Engineering Software 42(11), 976–991 (2011

Influence of blue stain on density and dimensional stability of Pinus sylvestris timber

La madera de Pinus sylvestris tiene interés comercial aunque su valor se reduce considerablemente cuando presenta hongos de azulado. En el presente estudio se apearon siete pinos procedentes de plantaciones españolas, y de los fustes se muestrearon 14 rodajas a diferentes alturas. Cuando éstas estaban parcialmente azuladas se labraron para obtener probetas pequeñas sin defectos anatómicos, sobre las que se determinó la densidad y además la estabilidad dimensional en volumen y en las tres dimensiones principales de la madera. En cada rodaja se compararon las propiedades físicas de las probetas completamente azuladas y las no azuladas, mediante el análisis de la varianza con un factor. El método permitió analizar la influencia específica del azulado eliminando otras fuentes de variación: factor árbol, altura en el fuste, anchura de anillos, presencia de albura y edad cambial. Solo en algunas rodajas la madera azulada de pino silvestre resultó signifi-cativamente diferente en densidad y contracción axial (madera azulada un 1% más densa y con la contracción axial un 13% mayor)Pinus sylvestris timber is commercially important, but its value is considerably decreased by the effects of blue stain fungi. Seven pine trees from Spanish plantations were felled for the study, and 14 discs were sampled from different heights in their stems. When the discs showed partial discolouration due to fungal infection, they were cut to produce small defect-free specimens for determining density and dimensional stability (in volume and in the three main dimensions of wood). The physical properties of fully stained and stain free specimens were compared, in each disc, by one-factor analysis of variance. This method enabled analysis of the specific influence of the blue stain fungi while avoiding other sources of variation: tree factor, height in the stem, ring width, presence of sapwood and cambial age. However, the only signicant differences between discoloured and unstained wood were in the density and axial shrinkage, in some discs (the density of the blue-stained wood was 1% higher and the axial shrinkage 13% higher than in the unstained wood)S

Influencia del azulado (mancha azul) en la densidad y estabilidad dimensional de la madera de Pinus sylvestris

La madera de Pinus sylvestris tiene interés comercial aunque su valor se reduce considerablemen-te cuando presenta hongos de azulado. En el presente estudio se apearon siete pinos procedentes de plantaciones españolas, y de los fustes se muestrearon 14 rodajas a diferentes alturas. Cuando éstas estaban parcialmente azuladas se labraron para obtener probetas pequeñas sin defectos anatómicos, sobre las que se determinó la densidad y además la estabilidad dimensional en volumen y en las tres dimensiones principales de la madera. En cada rodaja se compararon las propiedades físicas de las probetas completamente azuladas y las no azuladas, mediante el análisis de la varianza con un factor. El método permitió analizar la influencia específica del azulado eliminando otras fuentes de varia-ción: factor árbol, altura en el fuste, anchura de anillos, presencia de albura y edad cambial. Solo en algunas rodajas la madera azulada de pino silvestre resultó significativamente diferente en densidad y contracción axial (madera azulada un 1% más densa y con la contracción axial un 13% mayor). AbstractPinus sylvestris timber is commercially important, but its value is considerably decreased by the effects of blue stain fungi. Seven pine trees from Spanish plantations were felled for the study, and 14 discs were sampled from different heights in their stems. When the discs showed partial discoloura-tion due to fungal infection, they were cut to produce small defect-free specimens for determining density and dimensional stability (in volume and in the three main dimensions of wood). The phy-sical properties of fully stained and stain free specimens were compared, in each disc, by one-factor analysis of variance. This method enabled analysis of the specific influence of the blue stain fungi while avoiding other sources of variation: tree factor, height in the stem, ring width, presence of sapwood and cambial age. However, the only significant differences between discoloured and uns-tained wood were in the density and axial shrinkage, in some discs (the density of the blue-stained wood was 1% higher and the axial shrinkage 13% higher than in the unstained wood)

A Declarative Debugger for Maude Specifications: User Guide

We show in this guide how to use our declarative debugger for Maude specifications. Declarative debugging is a semi-automatic technique that starts from a computation considered incorrect by the user (error symptom) and locates a program fragment responsible for the error by asking questions to an external oracle, which is usually the user. In our case the debugging tree is obtained from a proof tree in a suitable semantic calculus; more concretely, we abbreviate the proof trees obtained from this calculus in order to ease and shorten the debugging process while preserving the correctness and completeness of the technique. We present the main features of our tool, what is assumed about the modules introduced by the user, the list of available commands, and the kinds of questions used during the debugging process. Then, we use several examples to illustrate how to use the debugger. We refer the interested reader to the webpage http://maude.sip.ucm.es/debugging, where these and other examples can be found together with more information about the theory underlying the debugger, its implementation and the Maude source files

Singular and Plural Functions for Functional Logic Programming

Functional logic programming (FLP) languages use non-terminating and non-confluent constructor systems (CS's) as programs in order to define non-strict non-determi-nistic functions. Two semantic alternatives have been usually considered for parameter passing with this kind of functions: call-time choice and run-time choice. While the former is the standard choice of modern FLP languages, the latter lacks some properties---mainly compositionality---that have prevented its use in practical FLP systems. Traditionally it has been considered that call-time choice induces a singular denotational semantics, while run-time choice induces a plural semantics. We have discovered that this latter identification is wrong when pattern matching is involved, and thus we propose two novel compositional plural semantics for CS's that are different from run-time choice. We study the basic properties of our plural semantics---compositionality, polarity, monotonicity for substitutions, and a restricted form of the bubbling property for constructor systems---and the relation between them and to previous proposals, concluding that these semantics form a hierarchy in the sense of set inclusion of the set of computed values. We have also identified a class of programs characterized by a syntactic criterion for which the proposed plural semantics behave the same, and a program transformation that can be used to simulate one of them by term rewriting. At the practical level, we study how to use the expressive capabilities of these semantics for improving the declarative flavour of programs. We also propose a language which combines call-time choice and our plural semantics, that we have implemented in Maude. The resulting interpreter is employed to test several significant examples showing the capabilities of the combined semantics. To appear in Theory and Practice of Logic Programming (TPLP)Comment: 53 pages, 5 figure