1. SCG Court: A Crowdsourcing Platform for Innovation Karl Lieberherr Northeastern University College of Computer and Information Science Boston, MA joint work with Ahmed Abdelmeged Karl Lieberherr Northeastern University College of Computer and Information Science Boston, MA joint work with Ahmed Abdelmeged Supported by Novartis

2. 4/24/20112Crowdsourcing SOLVE ORGANIZATIONAL PROBLEMS HOW TO COMBINE THE WORK OF HUNDREDS OF SCHOLARS? HOW TO AVOID ECONOMIC NON-SENSE HOW TO FOCUS SCHOLARS

3. Organizational Problem Solved How to organize a loosely coupled collaboration among several scholars to agree on claims that can be refuted or defended constructively using a dialog. – fair recognition of scholars strong scholars cannot be ignored – output: answer: “is claim refuted” plus the dialog When game is over: interested in – know-how! – list of claims that scholars agree with. 4/24/20113 defend(Alice,Bob,c) = ! refute(Alice,Bob,c) Crowdsourcing

4. Organizational Problem Solved How to design a happy scientific community that creates the science that society needs. Classical game solution: Egoistic scholars produce social welfare: knowledge base and know-how how to defend it. Control of scientific community – SCG rules – Specific domain 4/24/2011Crowdsourcing4 happy = no scholar is ignored, rich, immersive experience.

5. What is a loose collaboration? Scholars can work independently on an aspect of the same problem. Problem = decide which claims in playground to oppose or agree with. How is know-how combined? Using a protocol. – Alice claimed that for the input that Alice provides, Bob cannot find an output of quality q. But Bob finds such an output. Alice corrects. – Bug reports that need to be addressed and corrections. 4/24/20115Crowdsourcing Playground = Instantiation of Platform

6. Controlled Communication instead of Isolation 4/24/2011Crowdsourcing6 s1s2 s3s4 s1s2 s3s4 admin undesirable more learning and collaboration team evaluation s: scholar

7. Claims Protocol. Defines scientific discourse. Scholars make a prediction about their performance in protocol. Predicate that decides whether refutation is successful. Refutation protocol collects data for predicate. As a starter: Think of a claim as a mathematical statement: EA or AE. – all planar graphs have a 4 coloring. 4/24/20117Crowdsourcing

8. Benefits for Playground Designers Return On Investment for playground designers: a small investment in defining a playground (Domain=(Instance,Solution,valid,quality), Claim=(Protocol, etc.)) produces an interactive environment to assimilate and create domain knowledge. 4/24/20118Crowdsourcing

9. Benefits for Playground Designers 4/24/2011Crowdsourcing9 Playground Design Financial Incentive Organize the thought processes of hundreds of scholars to creatively focus on one problem

10. Benefits for Scholars Return on Investment for scholars and avatar designers: The SCG rules need to be learned only once because they are the same across playgrounds. A small investment in learning the SCG rules and a domain leads to numerous learning and teaching and innovation opportunities. The more a scholar teaches, the higher the scholar’s reputation. 4/24/201110Crowdsourcing

11. Benefits for Scholars: Immersion Experience 4/24/2011Crowdsourcing11 show me (solve) I challenge you (propose) you are wrong (oppose, teaching and learning) tell me (provide) me scholar ss s s Innovation: Scholars are free to invent; game rules don’t limit creativity; social engineering: answers to “why did I lose?” may lead to better solutions.

12. Global Warming Alice’ Claim: The earth is warming significantly. – Refutation protocol: Bob tries to refute. Alice must provide a data set DS satisfying a property defined precisely by the refutation protocol. Bob applies one of the allowed analysis methods M defined precisely by the refutation protocol. Bob wins iff M(DS) holds. 4/24/201112Crowdsourcing

13. Independent Set Protocol / claim: At Least As Good – Bob provides undirected graph G. – Bob computes independent set sB for G (secret). – Alice computes independent set sA for G. – Alice wins, if size(sA) >= size(sB). 4/24/201113Crowdsourcing

14. Overview 1.Organizational problem that SCG solves 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing14

15. Big Picture Weaker form of logic. Approximate truth. Don’t focus on proofs but on refutations. 4/24/2011Crowdsourcing15

16. 4/24/2011Crowdsourcing16 goodbad Logic with Soundness claims sentences not just true/false claims, but optimum/non- optimum claims: good: true/optimum bad: false/non-optimum

17. bad 4/24/2011Crowdsourcing17 good Scientific Community Game Logic with Community Principle agreed by two scholars disagreed by two scholars there exists two-party certificate to expose misclassification claims sentences agree c(informally): both successfully defend c and both successfully refute negation !c.

18. Comparison Logic and SCG Logic sentences – true – false proof for being true – proof system, checkable – guaranteed defense proof for being false – proof system, checkable – guaranteed refutation Universal sentences Scientific Community Game sentences = claims – good – bad evidence for goodness – defense, checkable – uncertainty of defense evidence for badness – refutation, checkable – uncertainty of refutation Personified sentences 4/24/2011Crowdsourcing18

19. Example: Highest Safe Rung You are doing stress-testing on various models of glass jars to determine the height from which they can be dropped and still not break. The setup for this experiment, on a particular type of jar, is as follows. Crowdsourcing194/24/2011

20. Highest Safe Rung Only two identical bottles to determine highest safe rung Alice Bob 20Crowdsourcing You have a ladder with n rungs, and you want to find the highest rung from which you can drop a copy of the jar and not have it break. We call this the highest safe rung. You have a fixed ``budget'' of k > 0 jars. 4/24/2011 admin

21. Highest Safe Rung Only two identical bottles to determine highest safe rung HSR(9,2) ≤ 4/9 I doubt it: refutation attempt! Alice Bob Alice constructs decision tree T of depth 4 and gives it to Bob. He checks whether T is valid. Bob wins if he finds a flaw. 21Crowdsourcing4/24/2011

22. 3 1 0 6 12 4 3 5 9 9 7 6 87 2 4 5 8 x yz yes no u highest safe rung Highest Safe Rung Decision Tree HSR(10,2)=5/10 22Crowdsourcing4/24/2011 Other playgrounds might have only two claims: C and !C.

23. bad 4/24/2011Crowdsourcing23 good Scientific Community Game Logic with Community Principle agreed by two scholars disagreed by two scholars there exists two-party certificate to expose misclassification claims sentences HSR(11,2)=4 HSR(27,3)=5 HSR(15,3)=5 HSR(57,4)=6 HSR(17,4)=4 HSR(5,1)=4 HSR(n,k)=q/n abbreviate as HSR(n,k)=k n: rungs k: to break q: questions HSR(8,3)=3

24. Community Principle for SCG Every faulty decision has a certificate to assign blame to the faulty decision maker. Certificate contains information from both parties. A certificate is a sequence of moves leading to a loss for the scholar making the faulty decision. – The certificate can be checked efficiently assuming all basic game operations (valid, belongsTo, quality) take constant time. 4/24/2011Crowdsourcing24

25. Example HSR(15,3)=5 This claim was misclassified as a good claim because both Alice and Bob could only find a decision tree of depth 5. Nina, a newcomer to the HSR scientific community, could find a decision tree of depth 4. Exposing the faulty decision of Alice and Bob. 4/24/2011Crowdsourcing25

26. Big Picture Replace soundness with community principle. Participants have to work hard to approximate soundness; if they don’t achieve soundness, they risk to be caught and risk to lose reputation. – as in a real scientific community: mistakes are made, even in mathematical journals. 4/24/2011Crowdsourcing26

27. What is SCG(X) Crowdsourcing27 no automation human plays full automation avatar plays degree of automation used by scholar some automation human plays 0 1 more applications: test constructive knowledge transfer to reliable, efficient software avatar Bob scholar Alice 4/24/2011

28. A Virtual World Avatar’s View Administrator Avatar Opponents’ communication, Feedback Claims, Instances, Solutions Results Agreed Claims: statements about algorithms = Social welfare Algorithms in Avatar 28Crowdsourcing4/24/2011 does simple checking (usually efficient) does complex work

29. Avatars propose and (oppose|agree) Crowdsourcing29 CA1 CA2 CA3 CA4 egoistic Alice egoistic Bob reputation 1000 reputation 10 CB1 CB2 opposes (1) provides instance (2) solves instance not as well as she expected based on CA2 (3) WINS! LOSES proposed claims transfer 200 Life of an avatar: (propose+ (oppose | agree)+ provide* solve*)* 4/24/2011

30. What Scholars think about! If I propose claim C, what is the probability that – C is successfully refuted – C is successfully strengthened If I try to refute claim C, what is the probability that I will fail. If I try to strengthen claim C, what is the probability that I will fail? 30Crowdsourcing4/24/2011

31. Essence of Game Rules actors: – proposer=verifier (1. arg to propose, oppose, refute, usually Alice), – opposer=falsifier (2. arg to propose, oppose, refute, usually Bob) LifeOfClaim(c) = propose(Alice,c) followed by (oppose(Alice,Bob,c)|agree(Alice,Bob,c)). oppose(Alice,Bob,c) = (refute(Alice,Bob,c)|strengthen(Alice,Bob,c,cs)), where stronger(c,cs). strengthen(Alice,Bob,c,cs) = !refute(Bob,Alice,cs). agree(Alice,Bob,c) = !refute(Alice,Bob,c) and !refute(Bob,Alice,c) and refute(Alice,Bob,!c) and refute(Bob,Alice,!c) 4/24/201131 blamed decisions: propose(Alice,c) refute(A,B,c) strengthen(Alice,Bob,c,cs) agree(A,B,c) Crowdsourcing

32. Winning/Losing propose(Alice,c), refutationTry(Alice,Bob,c) If Alice first violates a game rule, Bob is the winner. If Bob first violates a game rule, Alice is the winner. If none violate a game rule: the claim predicate c.p(Alice,Bob,in,out) decides. 4/24/201132Crowdsourcing

33. Game Rules for Playground legal(in) legal(out) valid(in,out) belongsTo(in, instanceSet) each move must be within time-limit 4/24/201133Crowdsourcing

34. Protocol Language ProtocolSpec = List(Step). Step = Action "from" Role. interface Role = Alice | Bob. Alice = "Alice". Bob = "Bob". interface Action = ProvideAction | SolveAction. ProvideAction = "instance". // solve the instance provided in // step # stepNo. // stepNo is 0-based. SolveAction = "solution" "of" int. 4/24/2011Crowdsourcing34 instance from Bob // r solution of 0 from Bob // sB for r solution of 0 from Alice // sA for r

35. How to achieve loosely coupled collaboration? Information exchange is based on values. Knowledge how to produce values is secret. Assign blame correctly to Alice or Bob based on outcome of refutation protocol. Every claim has a negation (using the idea of Hintikka’s dual game). Negation of HSR(n,k)=q: HSR(n,k)<q. 4/24/201135Crowdsourcing

36. Dual Game / Negation Each game G has a dual game which is the same as G except that the players Alice and Bob are transposed in both the rules for playing and the rules for winning. The game G(¬φ) is the dual of G(φ). 4/24/201136Crowdsourcing

37. How is collaboration working? Scholars make claim about their performance in a given context. Scholars make claim about the performance of their avatar in a given context. Opponent finds input in context that contradicts claim. Claim is refuted. 4/24/201137Crowdsourcing

38. Playground Design Define several languages – Instance – Solution – Claim InstanceSet Define protocol or reuse existing protocol. Implement interfaces for corresponding classes. 4/24/2011Crowdsourcing38

39. Who are the scholars? Students in a class room – High school – University Members of the Gig Economy – Between 1995 and 2005, the number of self- employed independent workers grew by 27 percent. Potential employees Anyone with web access; Intelligent crowd. 4/24/201139Crowdsourcing

40. How to engage scholars? Opposition Central to opposition is refutation. Claim defined by protocol. Simplest protocol: – Alice provides Input in. – Bob computes Output out: valid(in,out) – Alice defends if quality(in,out)<q. – Bob refutes if quality(in,out)>=q. Claims: C(q), q in [0,1]. 4/24/201140Crowdsourcing instance from Alice // in solution of 0 from Bob // out for in

41. Overview 1.Organizational problem solved by SCG 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing41

42. Crowdsourcing Active area: Recent Communication of the ACM article. Wikipedia, FoldIt, TopCoder, … We want a family of crowdsourcing systems with provable properties. 4/24/2011Crowdsourcing42

43. Crowdsourcing Platform Crowdsourcing – is the act of taking a job traditionally performed by a designated agent (usually an employee) and outsourcing it to an undefined, generally large group of people in the form of an open call. – enlists a crowd of humans to help solve a problem defined by the system owners. A crowdsourcing platform is a generic tool that makes it easy to develop a crowdsourcing system. 4/24/201143Crowdsourcing

44. Crowdsourcing Platform The job, target problem is – to solve instances of a problem and make claims about the solution process. – to build knowledge base of claims and techniques to defend the claims 4/24/201144Crowdsourcing

45. Requirements for Crowdsourcing Platform Find a good way to combine user contributions to solve the target problem. Find a good way to evaluate users and their contributions. Find a good way to recruit and retain users. 4/24/201145Crowdsourcing

46. SCG Court Web application Software developers register with SCG Court and choose playgrounds they want to compete in. They register their avatars in the appropriate playgrounds in time for the next tournament. Avatars get improved between tournaments based on ranking achieved and game history. 4/24/2011Crowdsourcing46

47. Combine user contributions Users build on each others work: strengthening and checking. Users check each others claims for correct judgment. – Claims are defended and refuted. Users trade reputation for information. – Example: HSR(15,3)=5 4/24/201147Crowdsourcing

48. Learning cycle Alice wins reputation with claim c because Bob made a wrong decision – Alice gives information about artifact related to c. Alice teaches Bob. Bob integrates information into his know-how. Bob learns from Alice. – Bob hopefully has learned enough and will no longer make a wrong decision about c. 4/24/2011Crowdsourcing48

49. Voting with Justification I vote – for this claim (agree) because I can defend it and refute its negation. – against this claim because I can oppose it (refute or strengthen). 4/24/201149Crowdsourcing

50. Evaluate users and their contributions Calculate reputation – confidence by the proposer that a claim is good (gc) – confidence by the opposer (refute or strengthen) that the claim is bad (bc) The scholars are encouraged to set their confidences truthfully. Otherwise they don't gain enough reputation or they lose too much reputation. 4/24/201150Crowdsourcing

51. Reputation Update Claimgoodbad proposeupdown opposedownup up: if you are good, there is a chance that you win down: if the other is good, there is a chance that you lose up: reputation goes up, but has to provide knowledge that might reveal secret technique. down: reputation goes down, but might gain knowledge that reveals secret technique. 4/24/201151Crowdsourcing

52. Reputation Update Claimgoodbad proposeupdown opposedownup up: if you are good, there is a chance that you win down: if the other is good, there is a chance that you lose confidence: proposer: claim is good: gc opposer: claim is bad: bc r = result of reputation protocol. Reputation update: r*gc*bc (various refinements are possible) 4/24/201152Crowdsourcing

53. Overview 1.Organizational problem solved by SCG 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing53

54. Formal Properties of SCG Soundness: – Only false claims are refuted. – Only true claims are defended. SCG is not sound because it adapts to the skill level of the scholars. E.g., – Alice proposes a false claim and still defends it, because Alice and Bob are weak, or – Alice proposes a true claim and does not defend it, because Alice is weak. We want to prove formal properties that don’t imply soundness. 4/24/2011Crowdsourcing54

55. Formal Properties Properties – Community Property – Equilibrium – Convergence Assumption: claims are bivalent (true or false); disallow indeterminate claims. 4/24/2011Crowdsourcing55

56. For every faulty decision action there exists an exposing reaction. decision propose(A,c): if c is not true, refute(A,B,c) or strengthen(A,B,c,cs) expose. decision oppose(Alice,Bob,c)|agree(Alice,Bob,c): – if Bob decides to oppose but does not oppose successfully, his oppose action is blamed. Bob discouraged to attack without good reason. – if Bob decides to agree but does not agree successfully, his agree action is blamed. 4/24/201156Crowdsourcing

57. Community Property For every faulty decision action there exists an exposing reaction that blames the bad decision. – Reasons: We want the system to be egalitarian. – It is important that clever crowd members can shine and expose others who don’t promote the social welfare of the community. Faulty decisions must be exposable. It may take effort. 4/24/201157Crowdsourcing

58. Community Property Alternative formulation If all decisions by Alice are not faulty, there is no chance of Alice losing against Bob. – if Alice is perfect, there is no chance of losing. If there exists a faulty decision by Alice, there is a chance of Alice losing against Bob. – egalitarian game 4/24/201158Crowdsourcing

59. Summary: faulty decisions 1.propose(Alice,c),c=bad 2.refute(Alice,Bob,c),c=good 3.agree(Alice,Bob,c),c=bad 4/24/201159Crowdsourcing

60. Summary: faulty decisions 1.propose(Alice,c),c=false 2.propose(Alice,c),c=not optimum, c=true 3.refute(Alice,Bob,c),c=true 4.strengthen(Alice,Bob,c,cs),c=optimum 5.strengthen(Alice,Bob,c,cs),c=false 6.agree(Alice,Bob,c),c=false 7.agree(Alice,Bob,c),c=not optimum, c=true 4/24/201160Crowdsourcing

61. Community Property Case 1 Alice’ decision propose(Alice,c) proposes claim c as a claim that is true. Let’s assume c is false. Alice introduced a fault into the knowledge base. There must be a reaction that assigns blame to Alice’ decision. Here it is: Bob decides to oppose: oppose(Alice,Bob,c), specifically to refute: refute(Alice,Bob,c). There must be a successful refutation. 4/24/201161Crowdsourcing 1. propose(Alice,c),c=false

62. Community Property Case 2 Alice’ decision propose(Alice,c) proposes claim c as a claim that is optimum. Let’s assume c is not optimum, but true, and can be strengthened. Alice introduced a fault into the knowledge base. There must be a reaction that assigns blame to Alice’ decision. Here it is: Bob decides to oppose: oppose(Alice,Bob,c), specifically to strengthen: strengthen(Alice,Bob,c,cs). There must be a choice for cs so that refute(Bob,Alice,cs) returns false, independent of Alice’ strategy. 4/24/201162Crowdsourcing 2. propose(Alice,c),c=not optimum, c=true

63. Community Property Case 3 Bob’s decision refute(Alice,Bob,c) is faulty, if c is true. Bob tries to introduce a fault into the knowledge base. There must be a reaction by Alice that assigns blame to Bob’ decision to refute. Because c is true, there must be a defense of c by Alice, i.e., refute(Alice,Bob,c) returns false independent of Bob’s strategy. Bob’s decision to refute is blamed. 4/24/201163Crowdsourcing 3. refute(Alice,Bob,c),c=true

64. Community Property Case 4 Bob’s decision strengthen(Alice,Bob,c,cs) is faulty, if c is optimum. Bob tries to introduce a fault into the knowledge base. There must be a reaction by Alice that assigns blame to Bob’s decision to strengthen. Because c is optimum, there must be a refutation of cs by Alice, i.e., refute(Bob,Alice,cs) returns true independent of Bob’s strategy. Bob’s decision to strengthen is blamed. 4/24/201164Crowdsourcing 4. strengthen(Alice,Bob,c,cs),c=optimum

65. Community Property Case 5 Bob’s decision strengthen(Alice,Bob,c,cs) is faulty, if c is false. Bob tries to introduce a fault into the knowledge base. There must be a reaction by Alice that assigns blame to Bob’s decision to strengthen. Because c is false, there must be a refutation of cs by Alice, i.e., refute(Bob,Alice,cs) returns true independent of Bob’s strategy. Bob’s decision to strengthen is blamed. 4/24/201165Crowdsourcing 5. strengthen(Alice,Bob,c,cs),c=false

66. Case 5 discussion Alice already made a faulty decision to propose c. But Bob did not catch that. In case 5 Bob makes things worse by trying to strengthen a false claim. Alice has an opportunity to force Bob to fail to defend his strengthened claim. 4/24/2011Crowdsourcing66

67. Community Property Case 6 Bob’s decision agree(Alice,Bob,c,) is faulty, if c is false. Let’s assume c is false. Bob tries to introduce a fault into the knowledge base. There must be a reaction by Alice that assigns blame to Bob’s decision to agree. Because c is false, there is a strategy for Alice so that refute(Bob,Alice,c) returns false independent of Bob’s strategy. Bob’s decision to agree is blamed. 4/24/201167Crowdsourcing 6. agree(Alice,Bob,c),c=false

68. Community Property Case 7 Bob’s decision agree(Alice,Bob,c,) is faulty, if c is not optimum. Let’s assume c is not optimum, but true. Bob tries to introduce a fault into the knowledge base. There must be a reaction by Alice that assigns blame to Bob’s decision to agree. Because c is not optimum and true, there must be a strengthening of c by Alice to cs, i.e., refute(Alice,Bob,cs) returns false independent of Bob’s strategy. Bob’s decision to agree is blamed. 4/24/201168Crowdsourcing 7. agree(Alice,Bob,c),c=not optimum, c=true

69. SCG Equilibrium reputations of scholars are stable the science does not progress; bugs are not fixed, no new ideas are introduced extreme example: All scholars are perfect: they propose optimal claims that can neither be strengthened nor refuted. Crowdsourcing694/24/2011

70. Claims Crowdsourcing70 0 1 quality strengthening correct valuation over strengthening true claims (defendable) false claims (refutable) 4/24/2011

71. Convergence if every faulty action is exposed, convergence guaranteed. 4/24/201171Crowdsourcing

72. Related Work Argumentation Theory Argumentation Mechanism Design – strategy-proof mechanism Logic – Paul Lorenzen Dialog games – Independence Friendly Logic by Hintikka/Sandu Logical games of imperfect information. 4/24/201172Crowdsourcing

73. Independence Friendly Logic (Hintikka and Sandu) Protocol / claim – Bob provides positive real number r in R +. – Bob computes square root sB of r in R (secret). – Alice computes square root sA of r in R. – Alice wins, if sA and sB are equal (within a small error bound). Claim is neither true nor false (Imperfect information). ForAll r in R + ForAll sB in R Exists sA/sB in R: (sA=sB) and (sB=B(r) and sA=A(r)) Exists sA/sB means that the Verifier’s choice prompted by Exists sA is independent of the Falsifier’s choice prompted by ForAll sB. 4/24/201173 Verifier = Alice Falsifier = Bob Crowdsourcing

74. In SCG Protocol Language instance from Bob // r solution of 0 from Bob // sB for r solution of 0 from Alice // sA for r 4/24/2011Crowdsourcing74

75. Independence Friendly Logic (IF Logic) Protocol / claim: At Least As Good – Bob provides undirected graph G. – Bob computes independent set sB for G (secret). – Alice computes independent set sA for G. – Alice wins, if size(sA) >= size(sB). Alice has a winning strategy: search for the maximum independent set. But does she have a practical winning strategy? 4/24/201175Crowdsourcing

76. Claims that are neither true nor false ForAll x Exists y/x (x=y) Has indeterminate truth in any model with cardinality > 1. Reason: game of imperfect information. Verifier and Falsifier will choose values for x and y without knowing each other’s choice. Classical logic is bivalent. IF logic is more expressive than ordinary first-order languages. 4/24/201176Crowdsourcing

77. Game-Theoretic Semantics Every sentence is associated to a game with two players: the Verifier (Alice) and the Falsifier (Bob). Universal quantifier prompts move of Falsifier. Existential quantifier prompts move of Verifier. A sentence is said to be true (false) if there exists a winning strategy for the Verifier (Falsifier). A sentence is said to be refuted (defended) if the Falsifier (Verifier) wins on a specific game. 4/24/201177Crowdsourcing

78. Long History (It came to light sometime later that C. S. Peirce had already suggested explaining the difference between ‘every’ and ‘some’ in terms of who chooses the object, in 1898) 4/24/2011Crowdsourcing78

79. Significance of Refutation or Defense Forget about winning strategies for Verifier and Falsifier. Want to come up with winning strategies incrementally. When Verifier wins a game, we have some evidence that claim is true. Falsifier is blamed for trying to refute. When Falsifier wins a game, we have some evidence that claim is false. Verifier is blamed for proposing the claim. 4/24/201179Crowdsourcing

80. Collaboration between Verifier (Alice) and Falsifier (Bob) IF formulas have special form: – ForAll i Exists oA: p(i,oA) and oA=A(i) and PB(i) – ForAll i ForAll oB Exists oA/oB: p(i,oA,oB) and oA=A(i) and oB=B(i) and PB(i) – Exists i ForAll oB: p(i,oB) and oB=B(i) and PA(i) We are interested in improving A,B and PB through playing the game several times. A is the know-how of Alice and B the know-how of Bob. A and B are functions. PB(i) is Bob’s provide relation to find hard inputs i. The claim makes a prediction about A and B and PB. A game defends the prediction or refutes it. 4/24/201180Crowdsourcing

81. Collaboration between Verifier (Alice) and Falsifier (Bob) After a successful defense, the blame is assigned to Bob. Specifically to Bob’s decision to oppose the claim. After a successful refutation, the blame is assigned to Alice. Specifically to Alice’ decision to propose the claim. It is the responsibility of Alice and Bob to assign the blame more specifically and improve their know-how about A, B, PA, PB and the claim. 4/24/201181Crowdsourcing

82. Overview 1.Organizational problem that SCG solves 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing82

83. SCG for different audiences Logicians Computer scientists Programmers Laymen Managers Experimental scientists 4/24/2011Crowdsourcing83

84. SCG for programmers Programming claims about programs – Provide input where claim fails. claims about problems – I have an algorithm that solves instances with quality q. Provide algorithm and other provides instance where algorithm does not achieve quality q. SCG claims – input = instance. claims – algorithm = instance – instance = solution 4/24/2011Crowdsourcing84

85. Comparison Logic and SCG Logic sentences – true – false proof for being true – proof system, checkable – guaranteed defense proof for being false – proof system, checkable – guaranteed refutation Universal sentences Scientific Community Game sentences = claims – good – bad evidence for goodness – defense, checkable – uncertainty of defense evidence for badness – refutation, checkable – uncertainty of refutation Personified sentences 4/24/2011Crowdsourcing85

86. Laymen Group problem solving for problems with constructive solutions. Solutions are evaluated by group. Reputation based: Scholar s1 is better than scholar s2 if reputation(s1) > reputation(s2). Game is egalitarian: scholars with good ideas can force reputation win. Scholars challenge each other and try to figure out each other’s solution processes. 4/24/2011Crowdsourcing86

87. Applications My Applications of SCG in teaching – Software Development classes Developing SCG Court Developing software for MAX CSP – Algorithms classes (e.g., HSR) Crowdsourcing know-how in constructive domains. 4/24/2011Crowdsourcing87

88. Claim involving Experiment Claim ExperimentalTechnique(X,Y,q,r) I claim, given raw materials x in X, I can produce product y in Y of quality q and using resources at most r. 88Crowdsourcing4/24/2011

89. Gamification of Software Development etc. Want reliable software to solve a computational problem? Design a game where the winning team will create the software you want. Want to teach a STEM domain? Design a game where the winning students demonstrate superior domain knowledge. Crowdsourcing Doesn’t TopCoder already do this? STEM = Science, Technology, Engineering, and Mathematics 894/24/2011

90. SCG and TopCoder SCG is an abstraction and generalization of TopCoder. Crowdsourcing904/24/2011

91. Planned Applications Require Prize Money IT recruiting tool: need employees good in a computational domain? Design a game and pick the winners. Need a software package for solving an optimization problem? Design a game and pick the winning avatar. 4/24/2011Crowdsourcing91

92. What we want Engage software developers – let them produce software that models an organism that fends for itself in a real virtual world while producing the software we want. Have fun. Focus them. – let them propose claims about the software they produce. Reward them when they defend their claims successfully or oppose the claims of others successfully. Crowdsourcing92 Clear FeedbackSense of Progress Possibility of Success Authenticity (Facebook) 4/24/2011

93. Overview 1.Organizational problem that SCG solves 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing93

94. Disadvantages Overhead for avatar developers – Overhead of learning SCG (rules) – Overhead of learning SCG Court (how to register your avatar) – Amortization: SCG(X1) -> SCG(X2) -> SCG(X3) Overhead for playground developers – Playgrounds need to be well tested (cheating) – Definition of what you want must be precise – Get what you ordered 4/24/2011Crowdsourcing94

95. Disadvantages of SCG The game is addictive. After Bob has spent 4 hours to fix his avatar and still losing against Alice, Bob really wants to know why! 95Crowdsourcing4/24/2011

96. Disadvantages of SCG The administrator for SCG(X) must perfectly supervise the game. – if admin does not, cheap play is possible – watching over the admin 96Crowdsourcing4/24/2011

97. How to compensate for those disadvantages Warn the scholars about addictive game. Use a gentleman’s security policy: report administrator problems, don’t exploit them to win. Occasionally have a non-counting “attack the administrator” competitions to find vulnerabilities in administrator. – both generic as well as X-specific vulnerabilities. 97Crowdsourcing4/24/2011

98. Overview 1.Organizational problem that SCG solves 2.What is SCG in detail? 3.Crowdsourcing 4.Formal Properties of SCG 5.Applications 6.Disadvantages 7.Conclusions 4/24/2011Crowdsourcing98

99. Conclusions SCG Court is a platform for creating happy communities of scholars/avatars that create science in specific domains. Solves organizational problems from introduction: lose coupling and effective combination of results, economically meaningful, fair evaluation. The egoistic scholars create social welfare: knowledge and the know-how to support it. Evaluates fairly, frequently, constructively and dynamically. Encourages retrieval of state-of-the-art know-how, integration and discovery. Challenges humans, drives innovation, both competitive and collaborative. 4/24/2011Crowdsourcing99

100. The End 4/24/2011Crowdsourcing100

101. Highest Safe Rung You are doing stress-testing on various models of glass jars to determine the height from which they can be dropped and still not break. The setup for this experiment, on a particular type of jar, is as follows. Crowdsourcing1014/24/2011

102. Highest Safe Rung Only two identical bottles to determine highest safe rung Alice Bob 102Crowdsourcing You have a ladder with n rungs, and you want to find the highest rung from which you can drop a copy of the jar and not have it break. We call this the highest safe rung. You have a fixed ``budget'' of k > 0 jars. 4/24/2011

103. Highest Safe Rung Only two identical bottles to determine highest safe rung HSR(9,2) ≤ 4 I doubt it: refutation attempt! Alice Bob Alice constructs decision tree T of depth 4 and gives it to Bob. He checks whether T is valid. Bob wins if he finds a flaw. 103Crowdsourcing4/24/2011

104. 3 1 0 6 12 4 3 5 9 9 7 6 87 2 4 5 8 x yz yes no u highest safe rung Highest Safe Rung Decision Tree HSR(9,2)=5 104Crowdsourcing4/24/2011

105. Finding solution for HSR(n,2) Approximate min x in [0,n] (n/x) + x Exact – MaxRungs(x,y) =MaxRungs(x-1,y-1)+MaxRungs(x-1,y) – MaxRungs(x, 2) = x + MaxRungs(x – 1, 2) – MaxRungs(0, 2) = 1 – Applied to HSR(9,2) MaxRungs(3,2) = 7 < 9 MaxRungs(4,2) = 11 > 9 105Crowdsourcing Keith Levin CS 4800 Fall 2010 MaxRungs(x,y) = the largest number of rungs we can test with y jars and x experiments. breaks at rootdoes not break at root Find minimum x, s.t. MaxRungs(x,2) > n 4/24/2011

106. MaxRungs MaxRungs(x,y) = sum [k=0.. y] binomial(x,k) All paths are of length x. At most k branches may be left branches. Note: y = x implies MaxRungs(x,y) = 2 x meaning a complete binary tree of depth x. Example: binomial(3,2)+binomial(3,1)+ binomial(3,0) = 7 Crowdsourcing1064/24/2011

107. Formal: HSR Domain: – Problem: (n,k), k <= n. – Solution: Decision tree to determine highest safe rung. – quality(problem, solution): depth of decision tree / number of rungs – valid(problem, solution): at most k left branches,... 107Crowdsourcing4/24/2011

108. Crowdsourcing108

109. Community Principle 2 If all decisions by Alice are good, there is no chance of Alice losing against Bob. – if Alice is perfect, there is no chance of losing. If there exists a bad decision by Alice, there is a chance of Alice losing against Bob. – egalitarian game 4/24/2011109Crowdsourcing

110. Bad Decisions (detectable efficiently during game) a.Proposing a claim and not supporting it. b.Opposing a claim and not opposing it successfully. c.Agreeing with a claim that one cannot defend nor refute its negation. 4/24/2011110Crowdsourcing

111. Under the Radar Under the radar: a game can progress without detectable faults of kinds a,b,c. Still not sound. With 7 fault kinds: if no faults: have soundness but cannot check it efficiently. With a,b,c: guaranteed loss if caught. 4/24/2011Crowdsourcing111

112. Questions from ETH Talk Michael Franz – electronic trading analogy, improve trading software over night Walter Huersch – value created by game: how to distribute it among participants? Based on reputation of scholars. – Volkswirtschaftlich vernueftig? Is it more efficient – get scholars to evaluate each other. Christoph Roduner – intranet: start collaboration. Game as collaboration starter. Focused brainstorming. Von CMU: Poersch? – How does it work with students. Mention baby avatar. MAX CSP. – Constructive nature. 4/24/2011Crowdsourcing112

113. Questions Thomas Gross – meta game: trying to break the game. – students pose each other questions and correct each other’s answers still need a TA because of unsoundness of game 4/24/2011Crowdsourcing113

114. Emanuele (by email) Claim sets to share (close under negation) – HSR(n,k)<=q – CNF(k)>=1-2 -k – MAX-CSP(R)>=t R – MAX(ProblemName,i)>=o MAX(NetworkFlow,g)>=f 4/24/2011Crowdsourcing114

115. Terminology decision or move. The following adjectives are equivalent – faulty – wrong – erroneous 4/24/2011Crowdsourcing115

116. Modified Game Build list of agreed claims: social welfare. Choose from list of allowed list of claims or from social welfare claims. Special rules for social welfare claims. Who has agreed with claim? Choose highest reputation member. Get’s extra time to defend. 4/24/2011Crowdsourcing116

117. certificate must be agreed by both parties, constructed according to refutation protocol. “true” claim that is false will be refuted “false” claim that is true will be defended faulty decisions about claims faulty decisions during game root cause analysis 4/24/2011Crowdsourcing117

118. Root Cause Analysis False claim in KB Alice proposed false claim. Bob failed to propose hard instance. Bob failed to solve instance well enough. 4/24/2011Crowdsourcing118

119. Root Cause Analysis True claim not in KB 4/24/2011Crowdsourcing119

120. claim HSR(16,3)=4: false How can it be agreed? Find DT of depth 4 with 16 leaves numbered 0..15. Cannot find a legal one. Agreement protocol – InstanceSet is one – if there is no solution and there is only one instance: everybody notices. No agreement is possible. 4/24/2011Crowdsourcing120

121. claim HSR(16,3)=5: non-optimal How can it be agreed? Find DT of depth 5 with 16 leaves numbered 0..15. Can find a legal one. Agreement protocol – InstanceSet is one – if there is no solution and there is only one instance: everybody notices. No agreement is possible. 4/24/2011Crowdsourcing121

122. |InstanceSet|=1, Minimization claim kindskinds(refined)agreement bad, non-optimalfalse (too low)no true (too high)yes good, optimaltrue (just right)yes 4/24/2011Crowdsourcing122 bad, nonoptimal, false claims are properly excluded from social welfare. Proof: none of the scholars participating in the agreement protocol will successfully defend because there is no solution. Because InstanceSet has size 1, there is only one instance to test.

123. Perfect Being perfect means to make perfect decisions. up: if you are perfect, you will not lose. down: if the other is perfect, you will not win. Claimgoodbad proposeupdown opposedownup up: if you are good, there is a chance that you win down: if the other is good, there is a chance that you lose 4/24/2011123Crowdsourcing

124. SCG from different perspectives Organizational Educational Logical 4/24/2011Crowdsourcing124

125. SCG for different audiences Logicians Computer scientists Programmers Laymen Managers Experimental scientists 4/24/2011Crowdsourcing125

126. SCG for programmers Programming claims about programs – Provide input where claim fails. claims about problems – I have algorithm that solves instances with quality q. Provide algorithm and other provides instance where algorithm does not achieve quality q. SCG claims – Provide instance where claim fails. claims – algorithm = instance – instance = solution 4/24/2011Crowdsourcing126

127. Comparison Logic and SCG Logic sentences – true – false proof for being true – proof system, checkable – guaranteed defense proof for being false – proof system, checkable – guaranteed refutation Universal sentences Scientific Community Game sentences = claims – good – bad evidence for goodness – defense, checkable – uncertainty of defense evidence for badness – refutation, checkable – uncertainty of refutation Personified sentences 4/24/2011Crowdsourcing127

128. Laymen Group problem solving for problems with constructive solutions. Solutions are evaluated by group. Reputation based: Scholar s1 is better than scholar s2 if reputation(s1) > reputation(s2). Game is egalitarian: scholars with good ideas can force reputation win. Scholars challenge each other and try to figure out each other’s solution processes. 4/24/2011Crowdsourcing128

129. Organizational Problem Solved Avoid economic inefficiency of some crowdsourcing systems: n participants solve the same problem independently without interaction. – reduced learning instead learning through interaction – isolation of participants instead integration and collaboration – exploitation of participants if they don’t make money, they have the opportunity to learn – evaluation is subjective evaluation is done by community 4/24/2011Crowdsourcing129

130. Avoid Economic Nonsense 1 contest, 500 responses, 1 selected. – no interaction between participants – 499 don’t learn much, nor put bread on their table. We want: each participant interacts with several others – feedback, opportunities for learning 4/24/2011Crowdsourcing130

131. A claim is information about one’s performance when interacting with another clever being. information about the performance of one’s program. 4/24/2011131Crowdsourcing

132. How to engage scholars? Several binary games between Alice and Bob. Alice must propose C or !C for one of the allowed C. Bob must agree with or oppose what Alice proposes. Agree(C) – Bob defends C against Alice. – Bob refutes !C against Alice. – Alice defends C against Bob. – Alice refutes !C against Bob. 4/24/2011132Crowdsourcing