Wiki systems have developed over the past years as lightweight, community-editable, web-based hypertext systems. With the emergence of Semantic Wikis, these collections of interlinked documents have also gained a dual role as ad-hoc RDF graphs. However, their roots lie at the limited hypertext capabilities of the World Wide Web: embedded links, without support for composite objects or transclusion. In this paper, we present experimental evidence that hyperstructure changes, as opposed to content changes, form a substantial proportion of editing effort on a large-scale wiki. The experiment is set in the wider context of a study of how the technologies developed during decades of hypertext research may be applied to improve management of wiki document structure and, with semantic wikis, knowledge structure

Boulain, Philip

Gibbins, Nicholas

Shadbolt, Nigel

English

Southampton (e-Prints Soton)

IntroductionExperimentResultsHyperstructure Maintenance Costs inLarge-scale WikisPhilip BoulainDepartment of Electronics and Computer ScienceUniversity of Southampton22nd April 2008Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOutline1 IntroductionContextRelationshipsSuggestions2 ExperimentHypothesisDatasetProcedure3 ResultsOverheadsConclusionsFuturePhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsBroader projectLooking at the potentially beneﬁcial relationships betweenOpen HypermediaInterconnected documentsSemantic WebInterconnected databasesWiki Wiki WebCommunal editing systemsPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsHypermediaLong-standing ﬁeld of research.How can documents expand beyond limitations of paper?Cross-referencing (hyperlinks).Sharing and re-use (composition and transclusion).“Essential feature” is “the process of tying two itemstogether” (linking).V. Bush.As We May Think.The Atlantic Monthly, 176:101–108, Jul 1945.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsOpen HypermediaMany types of links have been developed since.First-class: has identity distinct from content linked.N-ary: more than one source, one target.Typed: speciﬁes why or how documents related.Generic: endpoints selected by document criteria.Functional: endpoints from arbitrary functions.Open Hypermedia focuses on interoperation.Sharing hyperstructure with other systems.Applying hyperstructure to non-hypermedia resources.Both require non-embedded links.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsSemantic WebWorld Wide Web is a distributed set of interlinkeddocuments.The Semantic Web is distributed set of interlinked data.Discover and combine data from disparate sources as onemay discover and browse web pages.Core technology is the Resource Description Framework(RDF).RDF describes things using triples: subject has predicatevalue object.Subjects, predicates, and non-literal objects named usingURIs.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsWiki Wiki Web“A collection of Web pages which can be edited by anyone,at any time, from anywhere.”1Users can create pages with much of the structure andstyling of HTML web pages.But usually in a bespoke ad-hoc markup.Linking is web-style, like <a href=""></a>.But some wikis offer the ability to show backlinks.They can only do this because they are not distributed.The wiki system is aware of the entire document space.Massively successful.Wikipedia: over 2,000,000 articles.Low barrier to entry.1http://c2.com/cgi/wiki?WikiGettingStartedFaqPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsContextSuggestionsSuggested beneﬁtsWe have devised a mapping between hypermedia andsemantic wikis.Semantic wikis can be treated as simple hypermediasystems.Highlights the gaps in wiki capabilities.Anything but embedded, binary links!Generic links offer well-deﬁned version of WikiWords.First-class links make backlinks easy, even when editing.Transclusion allows content re-use and composition.MediaWiki templates are not transcluded at edit time; theyare not suitable for this.Adaptive hypermedia allows multiple contents per node,selected by e.g. level of detail.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsHypothesisDatasetProcedureHypothesisHypothesisManual editing of link structure, of a type which richer hypertextfeatures could automate, is a signiﬁcant overhead versuschanges to the text content.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsHypothesisDatasetProcedureEnglish WikipediaLarge, varied dataset: crosses many domains.Articles are heavily interlinked.Keeps complete history of editing process.Socially signiﬁcant: widely-used resource with activecommunity.Very, very big.84.6GB compressed; 2TB estimated uncompressed.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsHypothesisDatasetProcedureOverviewStream processing essential for this much data.Dumpbzcat// Trim articlesgzip// Trimmedzcat// Subsetgzip// Subset BC zcatGF Nearby revision comparisonBCGFWikiMarkup parsingBCGF BCGF  Abuse?Content? BCGFTemplates? BCGF Categories? BCGF Links? BCGFClassiﬁcations // Aggregate // StatisticsPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsHypothesisDatasetProcedureMeasuring text changesDump contains the page sources in wikimarkup.Need to parse this, at least approximately.Parse links to identify hyperstructure changes.Extract body text to identify content changes.Best-effort 42-state LL(k) ‘parser’.Need some metric of ‘how much this text has changed’.Best-effort Ω(n), O(n × m) string distance algorithm.Sliding window algorithm ran 0.01% subset in eightminutes, vs. 212 hours for Levenshtein.0.04% subset took 27 hours with sliding window, and wasinfeasible otherwise.Error could be large in some cases, but not near boundaryof major/minor thresholding.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsHypothesisDatasetProcedureCategoriesRevert Edit which simply undoes a previous edit.Content Major (nontrivial) edit of the page content.Minor Minor (trivial) edit of the page content.Category Edit to the categories of a page.List of Edit to a page which is an index to other pages.Indexing Edit to categories or listings, possibly both.Template Edit to the templates used by a page.Page link Edit to an internal page link.URL link Edit to a WWW URL link; usually external.Links Edit to page or URL links.Link only As ‘links’, but excluding major edits.Hyperstruct. Indexing, linking, or template use changes.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureIndex managementEdit type ProportionCategories 8.71%Lists 1.97%Overhead 10.56%0.01% subsetEdit type ProportionCategories 8.75%Lists 3.72%Overhead 12.34%0.04% subsetSerious effort spent on organising, not justproviding/updating, information.Semantic wiki: lists could be query results.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureLink management IEdit type ProportionLinks 49.60%Links only 35.53%Hyperstruct. 61.65%Content 17.81%Edit type RatioLinks 2.79Links only 2.00Hyperstruct. 3.460.01% subset, LevenshteinEdit type ProportionLinks 49.60%Links only 23.36%Hyperstruct. 61.65%Content 35.60%Edit type RatioLinks 1.39Links only 0.71Hyperstruct. 1.730.01% subset, ApproximatedEdit type ProportionLinks 49.56%Links only 25.24%Hyperstruct. 61.90%Content 35.99%Edit type RatioLinks 1.38Links only 0.70Hyperstruct. 1.720.04% subset, ApproximatedRatios of hyperstructure edits over content edits.Results consistent between 0.01% and 0.04%, so use0.01% Lev.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureLink management IIEdit type ProportionLinks 49.60%Links only 35.53%Hyperstruct. 61.65%Content 17.81%Edit type RatioLinks 2.79Links only 2.00Hyperstruct. 3.460.01% subset, LevenshteinEdit type ProportionLinks 49.60%Links only 23.36%Hyperstruct. 61.65%Content 35.60%Edit type RatioLinks 1.39Links only 0.71Hyperstruct. 1.730.01% subset, ApproximatedEdit type ProportionLinks 49.56%Links only 25.24%Hyperstruct. 61.90%Content 35.99%Edit type RatioLinks 1.38Links only 0.70Hyperstruct. 1.720.04% subset, ApproximatedTwice as many edits change just links as change content.Most of these (81%) are internal.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureEdit category distribution ICategory Registered Unregistered TotalList of 1,146 453 1,599Revert 4,069 679 4,748Category 6,121 954 7,075URL link 5,548 2,977 8,525Indexing 7,174 1,397 8,571Template 7,992 1,330 9,322Content 10,275 4,182 14,457Minor 13,776 9,961 23,737Link only 20,969 7,877 28,846Page link 27,205 8,871 36,076Links 29,671 10,606 40,277Hyperstruct. 38,358 11,701 50,059Total 57,463 23,733 81,196Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureEdit category distribution IICategory Registered Unregistered TotalList of 1,146 453 1,599Revert 4,069 679 4,748···Links 29,671 10,606 40,277Hyperstruct. 38,358 11,701 50,059Total 57,463 23,733 81,196Over 5% reverts: keeping Wikipedia stationary.Over half of edits adjusted the hyperstructure.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureUser edit counts100101102103104105101 102 103Numberof usersEdit count, ±5All usersRegisteredUnregisteredUser distribution over total number of edits made; 0.04% subsetPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureUser edit categories10110210310410510 20 30 40 50 60 70 80 90Numberof usersEdit count, ±5ContentPage link×××× ××× × ×××URL link ++++ + ++ + +++Template 4444 444 4 4 44Category♦♦♦♦ ♦♦♦ ♦ ♦ ♦♦RevertList of     User distribution over total number of edits made, by category; 0.04% subsetPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureEdit magnitudes1001011021031041051000 2000 3000 4000 5000 6000 7000Numberof editsEdit magnitude, ±50All usersRegisteredUnregisteredAll, approx.Edit distribution over magnitude of edit; 0.01% subsetPhilip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureLimitationsCannot reasonably detect some overheads automatically:Template substitution indistinguishable from adding markup.Same ﬁx applied to multiple pages.Reverts further back than the immediately precedingversion.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureExperimentHypothesisManual editing of link structure, of a type which richer hypertextfeatures could automate, is a signiﬁcant overhead versuschanges to the text content.Took random sample from English Wikipedia dataset.Processed edits into non-mutually-exclusive classes.Edits to the information content.versusEdits to the navigational structure.Compared editing effort expended on each class of edit.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureResultsMain observationsTwice as many edits changed links alone than content.10% of edits maintained manual indexes of pages.Richer hypermedia features can automate some of thisburden.Generic links can automate linking to articles.Semantic wiki features can also help.Lists can be generated by query on metadata.Hyperstructure matters!It is a major part of editor activity.It is worth working on improving it.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureMicro-scale experimentThis has been a macro-scale experiment.We are now ﬁnishing an experiment looking at themicro-scale.By what processes do editors make changes?Why do editors make changes?How can we prioritise improvements to support this?Initial results have been promising.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisIntroductionExperimentResultsOverheadsConclusionsFutureOpen Semantic Hyperwiki ModelDeﬁnes a wiki with open hypermedia features.First-class links, with edit-time embedding.Transclusion, including while editing.Generic and functional links.Parametric nodes and links.Full versioning, including links.Deﬁnes how this operates as a semantic wiki.From hyperlinks to RDF relations.Implementing in Weerkat: a highly ﬂexible and modularwiki system.Orthogonal with regards to storage, accounts, markup,policy, rendering...Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisSummary(Semantic) wikis are simple hypermedia systems.Analysis of edit type across large sample of Wikipedia:hyperstructure or content?Link editing alone is two times more common than contentediting.We can improve this situation by applying the lessons ofdecades of hypermedia research to these new hypermediasystems.Philip Boulain Hyperstructure Maintenance Costs in Large-scale WikisThanks for listeningQuestions?Philip Boulain Hyperstructure Maintenance Costs in Large-scale Wikis

Hyperstructure Maintenance Costs in Large-scale Wikis

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