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REACTIVECROWDSOURCINGAlessandro BozzonabMarco BrambillaaStefano CeriaAndrea MauriaaPolitecnico di MilanoDipartimento di Elettronica, Informazione e BioIngegneriabDelft University Of TechnologyDepartment of Software And Computer Technology

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Crowd Control is tough…• There are several aspects that makes crowdengineering complicated• Task design, planning, assignment• Workers discovery, assessment, engagementWednesday, May 15 Reactive Crowdsourcing 2http://xkcd.com/1060/

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Crowd Control is tough…Wednesday, May 15 Reactive Crowdsourcing 3• There are several aspects that makes crowdengineering complicated• Task design, planning, assignment• Workers discovery, assessment, engagement• Goal: taming the crowd• Cost• Time• Quality

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Crowd Control is tough…Wednesday, May 15 Reactive Crowdsourcing 4• There are several aspects that makes crowdengineering complicated• Task design, planning, assignment• Workers discovery, assessment, engagement• Goal: taming the crowd• Cost• Time• Quality• Motivation!• Need for higher level abstractions and tools• CONTROL as first-class citizen

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Reactive Crowdsourcing• A conceptual framework for modeling crowdsourcingcomputations and control requirements• Task Design• Reactive Control Design• Active Rule programming framework• Declarative rule language• A reactive execution environment for requirementenforcement and reactive execution• Based on the CrowdSearcher approachWednesday, May 15 Reactive Crowdsourcing 5

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Why Active Rules?• Crowdsourcing control typically focuses on task data• Execution results, agreement on truth value, workers performance• An active rule approach can provide• Ease of Use: control is easily expressible• Simple control data structures• Familiar formalism• Power: support to arbitrarily complex controls• Extensibility mechanisms• Automation: most active rules can be system-generated• Well-defined semantic• Flexibility: simple control variants have localized impact on therules set• Control isolationWednesday, May 15 Reactive Crowdsourcing 6

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The CrowdSearcher Approach• Human-Enhanced data management with social networksand Q&A systems as crowdsourcing platforms• Example: search task (WWW2012)Wednesday, May 15 Reactive Crowdsourcing 7Human Interaction ManagementSocialNetworksHumanComputationPlatformsQ&ASearch ExecutionEngineractionentQuery InterfaceSocialNetworksery AnswerSearch ExecutionEngineanInteractionanagementHumanQuery InterfaceLocalSocialNetworksQ&AQuery AnswerSearch ExecutionEngineHumanInteractionManagementSE AccessInterfaceHumanAccessInterfaceQuery InterfaceLocalSourceAccessInterfaceSocialNetworksQ&ACrowd-sourceplatformsQuery AnswerSearch ExecutionEngineHumanInteractionManagementSE AccessInterfaceHumanAccessInterfaceQuery InterfaceLocalSourceAccessInterfaceSocialNetworksQ&ACrowd-sourceplatformsQuery AnswerData Management SystemHuman AccessInterfaceRemote DataAccessLocal DataAccessSearch ExecutionEngineHumanInteractionManagementSE AccessInterfaceHumanAccessInterfaceQuery InterfaceLocalSourceAccessInterfaceSocialNetworksQ&ACrowd-sourceplatformsQuery AnswerSearch ExecutionEngineHumanInteractionManagementSE AccessInterfaceHumanAccessInterfaceQuery InterfaceLocalSourceAccessInterfaceSociaNetworQ&ACrowdsourceplatformQuery AnswerTaskHuman-EnhancedDataQueryResults

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• A simple abstract model• A task receives a list of input objects• Performers execute one or more operations upon them• The task produces a list of crowd-manipulated objects• A simple task design and deployment process, based on specific datastructures• created using model-driven transformations• driven by the task specificationThe Design ProcessWednesday, May 15 Reactive Crowdsourcing 8I O

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• A simple abstract model• A task receives a list of input objects• Performers execute one or more operations upon them• The task produces a list of crowd-manipulated objects• A simple task design and deployment process, based on specific datastructures• created using model-driven transformations• driven by the task specificationThe Design ProcessTaskSpecificationTask PlanningControlSpecificationWednesday, May 15 Reactive Crowdsourcing 9• Task Spec: task operations, objects, and performers Dimension Tables

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• A simple abstract model• A task receives a list of input objects• Performers execute one or more operations upon them• The task produces a list of crowd-manipulated objects• A simple task design and deployment process, based on specific datastructures• created using model-driven transformations• driven by the task specificationThe Design ProcessTaskSpecificationTask PlanningControlSpecificationWednesday, May 15 Reactive Crowdsourcing 10• Task Spec: task operations, objects, and performers Dimension Tables• Task Planning: work distribution  Execution Table for task monitoring

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• A simple abstract model• A task receives a list of input objects• Performers execute one or more operations upon them• The task produces a list of crowd-manipulated objects• A simple task design and deployment process, based on specific datastructures• created using model-driven transformations• driven by the task specificationThe Design ProcessTaskSpecificationTask PlanningControlSpecificationWednesday, May 15 Reactive Crowdsourcing 11• Task Spec: task operations, objects, and performers Dimension Tables• Task Planning: work distribution  Execution Table for task monitoring• Control Specification: task control policies  Control Mart

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Task Specification_1/3Wednesday, May 15 Reactive Crowdsourcing 12• Operation Types: Choice, Like, Score, Tag, Classify, Order, …• Operation Parameters: e.g. classification classesTasktIDopTypecategoriesTask Specification Task Planning Control SpecificationTask Configurationt1Classify Rep/Dem 

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Task Specification_2/3Wednesday, May 15 Reactive Crowdsourcing 13PoliticianclassifiedPartylastNamephotooID• Input Objects Schema: typed attributes• Output Attributes (according to task type)TasktIDopTypecategoriesTask Specification Task Planning Control SpecificationTask ConfigurationObjectSpecification o1 Obama http://…. ?????

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Task Specification_3/3Wednesday, May 15 Reactive Crowdsourcing 14PoliticianclassifiedPartylastNamephotooIDTask ConfigurationObjectSpecificationPerformerSpecification• Execution platform(s)• Qualifications, etc.TasktIDopTypecategories PerformernamepIDplatformTask Specification Task Planning Control Specification p1 Alessandro Facebook

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Task Planning_1/2• Organize the task in MicroTasks, and allocate input objects• μTaskObjectExecution  Designed for execution monitoring• Track performers responseclassifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDWednesday, May 15 Reactive Crowdsourcing 15PoliticianclassifiedPartylastNamephotooIDTasktIDopTypecategories PerformernamepIDplatformSplittingTask Specification Task Planning Control Specification mt1 O1 … …… … Facebook

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Task Planning_2/2• Assign performers to MicroTasks on platforms• Pull: dynamic assignment (First come - First served / Choice of theperformer)• Push: static assignment (Performers’ priority / Performer matching)classifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDWednesday, May 15 Reactive Crowdsourcing 16PoliticianclassifiedPartylastNamephotooIDTasktIDopTypecategories PerformernamepIDplatformSplitting AssignmentTask Specification Task Planning Control Specification mt1 O1 P1 Republican00:00:01 00:00:10 Facebook

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Control Specification_1/4Wednesday, May 15 Reactive Crowdsourcing 17Task Specification Task Planning Control Specification• Status Variable: tracking task and performers statusclassifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDPoliticianclassifiedPartylastNamephotooIDPerformernamepIDstatusplatformTasktIDopTypecategoriesstatus  Trusted/SpammerCreated/Planned/Closed 

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Control Specification_2/4Wednesday, May 15 Reactive Crowdsourcing 18Task Specification Task Planning Control Specification• Object : tracking objects statusclassifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDPoliticianclassifiedPartylastNamephotooIDPerformernamepIDstatusplatformTasktIDopTypecategoriesstatusObjectControl #demoID#eval#rep#curAnswer

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Control Specification_3/4Wednesday, May 15 Reactive Crowdsourcing 19Task Specification Task Planning Control Specification• Object : tracking object responses• Performer: tracking performer behavior (e.g. spammers)PerformerControl #rightpID#eval#wrongclassifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDPoliticianclassifiedPartylastNamephotooIDPerformernamepIDstatusplatformTasktIDopTypecategoriesstatusObjectControl #demoID#eval#rep#curAnswer

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Control Specification_4/4• Object : tracking object responses• Performer: tracking performer behavior (e.g. spammers)• Task: tracking task status: closing @completion, re-planWednesday, May 15 Reactive Crowdsourcing 20TaskControl#compObjtID#compExecPerformerControl #rightpID#eval#wrongclassifiedPartyplatformμTaskObjectExecutionμtIDstartTsendTsoIDpIDPoliticianclassifiedPartylastNamephotooIDPerformernamepIDstatusplatformTasktIDopTypecategoriesstatusObjectControl #demoID#eval#rep#curAnswerTask Specification Task Planning Control Specification

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Active Rules Language• Active rules are expressed on the previous datastructures• Event-Condition-Action paradigmWednesday, May 15 Reactive Crowdsourcing 21

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Active Rules Language• Active rules are expressed on the previous datastructures• Event-Condition-Action paradigm• Events: data updates / timer• ROW-level granularity• OLD  before state of a row• NEW  after state of a rowWednesday, May 15 Reactive Crowdsourcing 22e: UPDATE FOR μTaskObjectExecution[ClassifiedParty]

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Active Rules Language• Active rules are expressed on the previous datastructures• Event-Condition-Action paradigm• Events: data updates / timer• ROW-level granularity• OLD  before state of a row• NEW  after state of a row• Condition: a predicate that must be satisfied (e.g. conditions oncontrol mart attributes)Wednesday, May 15 Reactive Crowdsourcing 23e: UPDATE FOR μTaskObjectExecution[ClassifiedParty]c: NEW.ClassifiedParty == ’Republican’

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Active Rules Language• Active rules are expressed on the previous datastructures• Event-Condition-Action paradigm• Events: data updates / timer• ROW-level granularity• OLD  before state of a row• NEW  after state of a row• Condition: a predicate that must be satisfied (e.g. conditions oncontrol mart attributes)• Actions: updates on data structures (e.g. change attributevalue, create new instances), special functions (e.g. replan)Wednesday, May 15 Reactive Crowdsourcing 24e: UPDATE FOR μTaskObjectExecution[ClassifiedParty]c: NEW.ClassifiedParty == ’Republican’a: SET ObjectControl[oID == NEW.oID].#Eval+= 1

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Wednesday, May 15 Reactive Crowdsourcing 25e: UPDATE FOR ObjectControlc: (NEW.Rep== 2) or (NEW.Dem == 2)a: SET Politician[oid==NEW.oid].classifiedParty = NEW.CurAnswer,SET TaskControl[tID==NEW.tID].compObj += 1Rule ExampleTaskControl#compObjtID PerformerControlμTaskObjectExecutionPolitician classifiedPartyoIDPerformerTaskObjectControl #demoID#rep#evaltIDEvent

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Wednesday, May 15 Reactive Crowdsourcing 26e: UPDATE FOR ObjectControlc: (NEW.Rep== 2) or (NEW.Dem == 2)a: SET Politician[oid==NEW.oid].classifiedParty = NEW.CurAnswer,SET TaskControl[tID==NEW.tID].compObj += 1Rule ExampleTaskControl#compObjtID PerformerControlμTaskObjectExecutionPolitician classifiedPartyoIDPerformerTaskObjectControl #demoID#rep#evaltIDCondition

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Wednesday, May 15 Reactive Crowdsourcing 27e: UPDATE FOR ObjectControlc: (NEW.Rep== 2) or (NEW.Dem == 2)a: SET Politician[oid==NEW.oid].classifiedParty = NEW.CurAnswer,SET TaskControl[tID==NEW.tID].compObj += 1Rule ExampleTaskControl#compObjtID PerformerControlμTaskObjectExecutionPolitician classifiedPartyoIDPerformerTaskObjectControl #demoID#rep#evaltIDAction

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Wednesday, May 15 Reactive Crowdsourcing 28e: UPDATE FOR ObjectControlc: (NEW.Rep== 2) or (NEW.Dem == 2)a: SET Politician[oid==NEW.oid].classifiedParty = NEW.CurAnswer,SET TaskControl[tID==NEW.tID].compObj += 1Rule ExampleTaskControl#compObjtID PerformerControlμTaskObjectExecutionPolitician classifiedPartyoIDPerformerTaskObjectControl #demoID#rep#evaltIDAction

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Rule Programming Best Practice• We define three classes of rulesWednesday, May 15 Reactive Crowdsourcing 29μTaskObjectExecutionPerformerControlObjectControlTaskControlPolitician Performer Task

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Rule Programming Best PracticeWednesday, May 15 Reactive Crowdsourcing 30• We define three classes of rules• Control rules: modifying the control tables;μTaskObjectExecutionPerformerControlObjectControlTaskControlPolitician Performer Task

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Rule Programming Best PracticeWednesday, May 15 Reactive Crowdsourcing 31• We define three classes of rules• Control rules: modifying the control tables;• Result rules: modifying the dimension tables (object, performer, task);μTaskObjectExecutionPerformerControlObjectControlTaskControlPolitician Performer Task

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Rule Programming Best PracticeWednesday, May 15 Reactive Crowdsourcing 32• Top-to-bottom, left-to-right, evaluation• Guaranteed termination• We define three classes of rules• Control rules: modifying the control tables;• Result rules: modifying the dimension tables (object, performer, task);μTaskObjectExecutionPerformerControlObjectControlTaskControlPolitician Performer Task

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Rule Programming Best Practice• We define three classes of rules• Control rules: modifying the control tables;• Result rules: modifying the dimension tables (object, performer, task);• Execution rules: modifying the execution table, either directly or through re-planningWednesday, May 15 Reactive Crowdsourcing 33μTaskObjectExecutionPerformerControlObjectControlTaskControlPolitician Performer Task• Termination must be proven (Rule precedence graph has cycles)

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Experimental Evaluation• GOAL: demonstrate the flexibility and expressive powerof reactive crowdsourcing• 3 experiments, focused on Italian politicians• Parties: Human Computation  affiliation classification• Law: Game With a Purpose  guess the convicted politician• Order: Pure Game  hot or not• 1 week (November 2012)• 284 distinct performers• Recruited through public mailing lists and social networksannouncements• 3500 Micro TasksWednesday, May 15 Reactive Crowdsourcing 34

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Politician Affiliation• Given the picture and name of a politician, specify his/her politicalaffiliation• No time limit• Performers are encouraged to look up online• 2 set of rules• Majority Evaluation• Spammer DetectionWednesday, May 15 Reactive Crowdsourcing 35

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Results – Majority Evaluation_1/3Wednesday, May 15 Reactive Crowdsourcing 3630 object; object redundancy = 9;Final object classification as simple majority after 7 evaluations

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Results - Majority Evaluation_2/3Wednesday, May 15 Reactive Crowdsourcing 37Majority @7Early Majority @3 R @7-27% executions-18% precision%ofCompl.Objects00.10.20.30.40.50.60.70.80.91.0Precision00.10.20.30.40.50.60.70.8#Executions0 10 20 30 40 50 60 70 80 90Final object classification as total majority after 3 evaluationsOtherwise, re-plan of 4 additional evaluations. Then simple majority at 7

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Results - Majority Evaluation_3/3Wednesday, May 15 Reactive Crowdsourcing 38Majority @7Early Majority @3 R @7Majority @3 R @5 R @7-23% executions+26% precision+50% precision%ofCompl.Objects00.10.20.30.40.50.60.70.80.91.0Precision00.10.20.30.40.50.60.70.8#Executions0 10 20 30 40 50 60 70 80 90Final object classification as total majority after 3 evaluationsOtherwise, simple majority at 5 or at 7 (with replan)

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Results – Spammer Detection_1/2Wednesday, May 15 Reactive Crowdsourcing 39New rule for spammer detection without ground truthPerformer correctness on final majority. Spammer if > 50% wrong classificationsMajority @3 R @5 R @7Majority @3 R @5 R @7 - Spammer Detection+46% executions+1.5% precision%ofCompl.Objects00.10.20.30.40.50.60.70.80.91.0Precision00.10.20.30.40.50.60.70.8#Executions0 10 20 30 40 50 60 70 80 90

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A Short CrowdSearcher DemoWednesday, May 15 Reactive Crowdsourcing 40

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Summary• Results• An integrated framework for crowdsourcing task design and control• Well-structured control rules with some guarantees of termination• Support for cross-platform crowd interoperability• A working prototype  crowdsearcher.search-computing.org• Forthcoming• Exploitation of interoperability• Expertise finding• Dynamic planning• Integration with other social-networks and human computationplatformsWednesday, May 15 Reactive Crowdsourcing 41

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QUESTIONS?Wednesday, May 15 Reactive Crowdsourcing 42