6th International Workshop on Confluence6th International Workshop on ConfluenceWe present a useful web interface for tools that participate in the annual confluence competition

6th International Workshop on Confluence

Middeldorp, A

Nagele, J

English

Queen Mary Research Online

CoCoWebA Convenient Web Interface for Confluence Tools∗Julian Nagele and Aart MiddeldorpDepartment of Computer Science, University of Innsbruck, Austria{julian.nagele,aart.middeldorp}@uibk.ac.atAbstractWe present a useful web interface for tools that participate in the annual confluencecompetition.1 IntroductionIn recent years several tools have been developed to automatically prove confluence and relatedproperties of a variety of rewrite formats. These tools compete annually in the confluencecompetition [1] (CoCo).1 Most of the tools can be downloaded, installed, and run on one’s localmachine, but this can be a painful process.2 Few confluence tools—we are aware of CO3 [4],ConCon [5], and CSI [3, 7]—provide a convenient web interface to painlessly test the status of asystem that is provided by the user.Inspired by the latest web interface of CSI [3], in this note we present CoCoWeb, a webinterface that provides a single entry point to all tools that participate in CoCo. CoCoWeb isavailable athttp://cl-informatik.uibk.ac.at/software/cocowebThe typical use of CoCoWeb will be to test whether a given confluence problem is known to beconfluent or not. This is useful when preparing or reviewing an article, preparing or correctingexams about term rewriting, and when contemplating to submit a challenging problem tothe confluence problems (Cops)3 database. In particular, CoCoWeb is useful is when lookingfor (killer) examples to illustrate a new technique. For instance, in [2] a rewrite system ispresented that can be shown to be confluent with the technique introduced in that paper. Theauthors write “Note that we have tried to show confluence [ . . . ] by confluence checker ACP andSaigawa, and both of them failed.” Despite having an easy to use web interface, CSI was nottried. CoCoWeb could also be useful for the CoCo steering committee when integrating newlysubmitted problems into Cops.The tools run on the same hardware, which is compatible with a single node of StarExec [6]that is used for CoCo, allowing for a proper comparison of tools.In the next section we present the web interface of CoCoWeb by means of a number ofscreenshots. Implementation details are presented in Section 3 and in Section 4 we list somepossibilities for extending the functionality of CoCoWeb in the future.∗This work is supported by the Austrian Science Fund (FWF): project P27528.1http://coco.nue.riec.tohoku.ac.jp2StarExec provides a VM Image with their environment, which can helpful in case a local setup is essential.3http://cops.uibk.ac.atarXiv:1708.07876v1  [cs.LO]  25 Aug 2017CoCoWeb Nagele and MiddeldorpFigure 1: The entry page of CoCoWeb.2 Web InterfaceFigure 1 shows a screenshot of the entry page of CoCoWeb. Problems can be entered in threedifferent ways: (1) using the text box, (2) uploading a file, (3) entering the number of a systemin Cops. The tools that should be executed can be selected from the tools panel on the left.Tools are grouped into categories, similar to the grouping in CoCo except that we merged theFigure 2: Problem and tool selection in CoCoWeb.2CoCoWeb Nagele and Middeldorpcertified categories with the corresponding uncertified categories. Multiple tools can be selected.This is illustrated in Figure 2. Here we selected the CoCo 2016 and 2015 versions of ACPH andthe CoCo 2015 version of CSÎ ho, and Cop 500 is chosen is input problem.The screenshot in Figure 3 shows the output of CoCoWeb after clicking the submit button.The output of the selected tools is presented in separate tabs. The colors of these tabs revealuseful information: Green means that the tool answered yes, red (not shown) means that thetool answered no, and a maybe answer or a timeout is shown in blue. By clicking on a tab, thecolor is made lighter and the output of the tool is presented. The final line of the output istiming information provided by CoCoWeb.The final screenshot (in Figure 4) is concerned with the example in [2] that we referred to inthe introduction.3 ImplementationMost of CoCoWeb is built using PHP. User input in forms, i.e., rewrite systems and toolselections, is sent using the HTTP POST method. The dynamic parts of the website, namelyfolding and unfolding in the tool selection menu and the tabs used for viewing tool output areimplemented using JavaScript.To layout the tool selection menu we made extensive use of CSS3 selectors. For instance,the buttons to select tools are implemented as checkboxes with labels that are styled accordingto whether the checkbox is ticked or not:.tools input[type="checkbox"]:checked + label {color: white;background-color: #799BB3;}Figure 3: Result displaying in CoCoWeb.3CoCoWeb Nagele and MiddeldorpFigure 4: Testing Example 14 from [2] in CoCoWeb.Drawing the edges of the tree menu is also done using CSS, relying mainly on its ::beforeselector.The content of the tool menu, i.e., years, the grouping by categories, and the actual tools, isgenerated automatically from a directory tree that has the structure of the menu in CoCoWeb.There small configuration files reside that specify how the tools are to be run, in case they areselected. Two environment variables are set in such a file, for example the one for the 2012version of Saigawa reads as follows:TOOLDIR="Saigawa-2012/bin"TOOL="./starexec_run_saigawa -t $TO $FILE"The variable TOOLDIR specifies the directory that contains the tool binary, while TOOL gives thetool invocation, which in turn refers to TO, the timeout, and FILE, the input rewrite system.Using such configuration files tools are run using the following script, whose first and secondargument are the configuration of the tool and input rewrite system respectively:DIR=$(pwd -P)FILE=$(readlink -f $2)TO=59TOT=61TOK=63source $1pushd $DIR/bin/$TOOLDIR > /dev/null/usr/bin/time -f "\nTook %es" timeout -k $TOK $TOT $TOOLpopd > /dev/nullThe script uses three different timeouts: TO is the timeout passed to the tool itself if supported,while after TOT and TOK the signals SIGTERM and SIGKILL are sent to the tool in case it did4CoCoWeb Nagele and Middeldorpnot terminate on its own volition. When multiple tools are selected, CoCoWeb runs themsequentially, in order to avoid interference.4 Possible ExtensionsWe conclude this note with some ideas for future extensions of the functionality of CoCoWeb.• By analyzing the format of the input problem, it is often possible to determine the categoryto which the problem belongs. This information can then be used to restrict tool selectionaccordingly.• Adding support for other competition categories like ground confluence and unique normalforms is an obvious extension. This, however, limits the possibilities to restrict toolselection mentioned in the previous item.• Selected tools are executed sequentially and so if many tools are selected, the 60 secondstime limit per tool may result in an unacceptably slow response. In that case a timeroption is a welcome feature.References[1] T. Aoto, N. Hirokawa, J. Nagele, N. Nishida, and H. Zankl. Confluence Competition 2015. In Proc.25th International Conference on Automated Deduction, volume 9195 of Lecture Notes in ArtificialIntelligence, pages 101–104, 2015. doi: 10.1007/978-3-319-21401-6_5.[2] S. Ishizuki, M. Oyamaguchi, and M. Sakai. Conditions for confluence of innermost terminating termrewriting systems. In Proc. 5th International Workshop on Confluence, pages 70–74, 2016. Availablefrom http://cl-informatik.uibk.ac.at/iwc/iwc2016.pdf.[3] J. Nagele, B. Felgenhauer, and A. Middeldorp. CSI: New evidence – a progress report. In Proc.26th International Conference on Automated Deduction, volume 10395 of Lecture Notes in ArtificialIntelligence, pages 385–397, 2017. doi: 10.1007/978-3-319-63046-5_24.[4] N. Nishida, T. Kuroda, M. Yanagisawa, and K. Gmeiner. CO3: A COnverter for proving COnfluenceof COnditional TRSs (version 1.2). In Proc. 4th International Workshop on Confluence, page 42,2015. Available from http://cl-informatik.uibk.ac.at/iwc/iwc2015.pdf.[5] T. Sternagel and A. Middeldorp. Conditional confluence (system description). In Proc. Joint25th International Conference on Rewriting Techniques and Applications and 12th InternationalConference on Typed Lambda Calculi and Applications, volume 8560 of Lecture Notes in ComputerScience (Advanced Research in Computing and Software Science), pages 456–465, 2014. doi: 10.1007/978-3-319-08918-8_31.[6] A. Stump, G. Sutcliffe, and C. Tinelli. StarExec: A cross-community infrastructure for logic solving.In Proc. 7th International Joint Conference on Automated Reasoning, volume 8562 of Lecture Notesin Artificial Intelligence, pages 367–373, 2014. doi: 10.1007/978-3-319-08587-6_28.[7] H. Zankl, B. Felgenhauer, and A. Middeldorp. CSI – A confluence tool. In Proc. 23rd InternationalConference on Automated Deduction, volume 6803 of Lecture Notes in Artificial Intelligence, pages499–505, 2011. doi: 10.1007/978-3-642-22438-6_38.5

CoCoWeb - A Convenient Web Interface for Confluence Tools

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CoCoWeb - A Convenient Web Interface for Confluence Tools

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