1/12 Project DIANE: Project KRASH: A Taxonomy of Incentive Patterns - The Design Space of Incentives for Cooperation Universität Karlsruhe (TH), Germany Institute for Program Structures und Data Organization Universität Karlsruhe (TH) GERMANY Second International Workshop on Agents and Peer-to-Peer Computing (AP2PC 2003) held at AAMAS 2003 Melbourne, Australia, July 14th, 2003 Philipp Obreiter and Jens Nimis

2/12 Overview Project background and motivation –P2P, Ad-hoc systems –Multi-Agent Systems (Un-)Cooperative Behavior Incentive Patterns –Characteristics –Taxonomy Conclusion

3/12 Incentives in P2P and Ad Hoc Networks Example DIANE: E-Learning in Ad-hoc Networks Anna More on SQL? Official SQL Slides Summary on 2PC Exercise Sheet on UML Exercise Sheet on SQL Solution to SQL Sheet Bob  Carl

4/12 Incentives in Multi-Agent Systems Example Agent.Enterprise : Distributed Supply Chain Management intraplantinterplantexternal controlexecuteplan KRASH- System IntaPS- System Internal PPC MAS dispoweb Supply Chain Control MAS Supply Chain Scheduling MAS OEM Customer

5/12 Common Characteristics P2P-Networks, Ad-Hoc-Networks and Multi-Agent Systems consist of autonomous entities, need cooperation to exploit synergies, and consume (scarce) resources when cooperating. service consumerprovider remuneration Abstract model of elementary cooperation:  Cooperative behaviour must be stimulated.

6/12 Taxonomy of Uncooperative Behavior uncooperative behavior misbehavior venial noncooperation reasonableunreasonable malicious behavior profitable misbehavior unprofitableprofitable lavish behaviorselfish behavior by providerby consumer

7/12 Incentive Schemes and Incentive Patterns Incentive Pattern pattern of stimulating cooperation – comprises set of abstract mechanisms – generally introduces a specific type of remuneration Incentive Scheme applies specific incentive patterns aims at – restricting misbehavior – exempting venial noncooperation from punishment

8/12 General Characteristics of Incentive Patterns Roles (symmetric vs. asymmetric) Remuneration Type (e.g. checks, reputation,…) Storage (Where is the remuneration stored?) Granularity (regarding the provided service) Assessment (Who assesses the remuneration ? ) Coping with Selfishness Lavishness Venial noncooperation Trust Trusted entities Anonymity Scalability (number of entities)

9/12 Taxonomy of Incentive Patterns incentive patterns trust based patterns stimulated by trust trade based patterns stimulated by action in return collective static community (remuneration) dynamic barter trade immediate bond based deferred Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

10/12 Characteristics of Incentive Patterns - Summary Pattern Characteristics Collec- tives Commu- nities Barter Trade Bearer Banking Bank Notes Bills Rolesasymmetricsymmetricasymmetric Remu- neration Type none reputation service in return notebillcheckbanknote Storage Site consumer−provider/bearer Remu- neration Granularity none arbitraryservice fraction of service arbitrarybanknote Assess- ment consumer provider/ consumer provider/bearermarket Copes with Selfishness + − ++ Lavishness++o+ Venial non- cooperation o−−o Trust Trustedconsumer none cons. cons./ debtor cons./ bank (cons./) centr. auth. Anonymity−+−(−)(−)o+ Scalability− −+o+++

11/12 Conclusion and Current Work Conclusion In presence of autonomous entities cooperative behaviour must be stimulated. Stimulating cooperative behavior –means restricting uncooperative behavior. –can be achieved by incentive schemes according to certain incentive patterns. Incentive patterns open up a design space that can be exploited by comparing their characteristics to the requirements of the target system. Current Work More Characteristics  finer granularity of patterns Composition of incentive pattern in one and over different entity layers

12/12 Thank you! More information (especially the technical report) on our project web page: Are there any questions? Thank you for your attention!

13/12 Backup Slides

14/12 Taxonomy of Incentive Patterns incentive patterns trust based patternstrade based patterns stimulated by trust stimulated by action in return collective static

15/12 The Collective Pattern Incentive: Membership in the same collective Properties: Mutual trust Unconditional operation PatternCollective Rolesasymetric Remuneration Typenone Storage Site none Remuneration Granularitynone Assessmentnone Copes with Selfishness+ Lavishness+ Venial non- cooperation + Trust Trustedconsumer Anonymity- Scalability--

16/12 Taxonomy of Incentive Patterns incentive patterns trust based patternstrade based patterns stimulated by trust stimulated by action in return collective static community (remunerating) dynamic

17/12 The Community Pattern Incentive: Reputation within a group Properties: Reputation gained by providing services Good reputation required in order to consume services PatternCommunity Rolesasymmetric Remuneration Typereputation Storage Site consumer Remuneration Granularityarbitrary Assessmentconsumer Copes with Selfishness- Lavishness- Venial non- cooperation o Trust Trustedconsumer Anonymity - Scalability-

18/12 Taxonomy of Incentive Patterns incentive patterns trust based patternstrade based patterns stimulated by trust stimulated by action in return collective static community (remuneration) dynamic barter trade immediate

19/12 The Barter Trade Pattern Incentive: Direct exchange of services Properties: Consumer acts as provider simultaneously PatternBarter Trade Rolessymmetric Remuneration Type service in return Storage Site - Remuneration Granularity- Assessment consumer/ provider Copes with Selfishness+ Lavishness+ Venial non- cooperation - Trust Trustednone Anonymity+ Scalability+

20/12 Taxonomy of Incentive Patterns incentive patterns trust based patternstrade based patterns stimulated by trust stimulated by action in return collective static community (remuneration) dynamic barter trade immediate bond based deferred Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

21/12 The Bearer Notes Pattern Incentive: Consumer promises service in return Properties: Similarity with community pattern (explicit) Pattern Bearer Notes Rolesasymmetric Remuneration Typenote Storage Site provider/ bearer Remuneration Granularity fraction of service Assessment provider/ bearer Copes with Selfishness+ Lavishness+ Venial non- cooperation − Trust Trustedconsumer Anonymity− Scalabilityo Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

22/12 The Bearer Bills Pattern Incentive: Consumer promises the provision of a service in return by the debtor Properties: Provider has to trust in the relationship between consumer and debtor PatternBearer Bills Rolesasymmetric Remuneration Typebill Storage Site provider/ bearer Remuneration Granularity fraction of service Assessment provider/ bearer Copes with Selfishness+ Lavishnesso Venial non- cooperation o Trust Trusted consumer/ debtor Anonymity(−) Scalabilityo Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

23/12 The Banking Pattern Incentive: Balance of one's account Properties: Consumer hands over a check Provider cashes it PatternBanking Rolesasymmetric Remuneration Typecheck Storage Site provider/ bearer Remuneration Granularityarbitrary Assessment provider/ bearer Copes with Selfishness+ Lavishness+ Venial non- cooperation o Trust Trusted consumer/ bank Anonymityo Scalability+ Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

24/12 The Bank Notes Pattern Incentive: Consumer hands over banknotes to the provider Properties: Bank notes promises a service in return by a central authority PatternBank Notes Rolesasymmetric Remuneration Typebanknote Storage Site provider/ bearer Remuneration Granularitybanknote Assessmentmarket Copes with Selfishness+ Lavishness+ Venial non- cooperation o Trust Trusted (consumer)/ centr. auth. Anonymity+ Scalability++ Debtor Issuer Any party Dedicated third party is debtor bearer notes pattern banknotes pattern is not debtor bearer bills pattern banking pattern

25/12 Backup Slides 2

26/12 Ad Hoc Networks: Absence of Infrastructure

27/12 Conceptual Layering Application Discovery Transport Network Link User Interface Application Discovery Transport Network Link User Interface device Adevice B autonomy border

28/12 Exemplification of Uncooperative Behavior Application Discovery Transport Network Link User Interface Application Discovery Transport Network Link User Interface Dropping packets under heavy load  venial noncooperation Application Network Transport Discovery DoS attack  malicious behavior Drop other devices' advertisements  selfish behavior Wastefully consume other devices' services  lavish behavior

29/12 Autonomy Autonomous devices devices are free to cooperate or not Sound assumption tampered devices re-engineered protocol stacks absence of an enforcing authority Devices tend to be uncooperative scarceness of resources (e.g. battery power)  cooperative behavior must be stimulated

30/12 Abstract Model of Elementary Cooperation PrincipalAgent action remuneration service ConsumerProvider check Application Layer forwarding SenderRouter reputation Network Layer

31/12 Incentive Scheme Issues (1): Trust Trust prerequisite for remuneration mechanisms an incentive for cooperation Static Trust certification of an entity's trustworthiness requires cryptographic infrastructure Dynamic Trust arises from prior experiences need for reputation management considers behavioral change

32/12 Incentive Scheme Issues (2): Transactions Transaction encompasses elementary cooperation agent executes action iff principal remunerates agent Negotiation phase agreement on the action and remuneration determined by the respective cost/profit ratios Processing phase assertion of atomicity seems daunting approximated atomicity by interleaving action and remuneration efficient low value transactions by aggregating actions and remunerations

33/12 Incentive Scheme Issues (3): Remuneration Remuneration type different types have been proposed most popular types checks, e.g., TermiNodes reputation, e.g., Marti et al 2000 Transferability passing on checks disseminating reputation Convertibility cashing checks reconciling user and device views of reputation

34/12 Account Based Incentive Schemes: Properties Remuneration mechanism every entity possesses an account accounts stored on virtual banks principal issues a check agent accesses a virtual bank in order to credit its account Implementation requires static trust mechanisms virtual banks managed by dedicated devices banker nodes accessibility? accounts distributed to account holders tamper resistant hardware

35/12 Reputation Based Incentive Schemes: Properties Remuneration mechanism principal adapts agent's reputation according to its action agent might decrease principal's reputation agent only cooperative if principal has good reputation Implementation couple trust and remuneration local views of reputation may be kept local shared, i.e., disseminated increases effectiveness introduces further opportunities for misbehavior requires stable or localized cooperation patterns

36/12 Taxonomy of Incentive Patterns incentive patterns trust based patternstrade based patterns stimulated by trust stimulated by action in return collective static community (remuneration) dynamic barter trade immediate bank notesbearer notesbearer billsbanking bond based deferred

37/12 Incentive Schemes: Classification Approach Properties Termi- Nodes SpriteAPERPG Watchdog/ Pathrater CON- FIDANT CORE Scope Coop. domainN/T NNNNN Selfishnessyes - Lavishnessyes ---- Maliciousnessyes- - - Remuneration typechecksreputation Transferability/ Dissemination yes--- only positive Convertibility-yes ---- Sniffing----yes Truststaticdynamic Implemen- tation Tamper resistance security modules Cryptographic infrastructure public key ---- Trans- action Negotiationyes Processingaction/remuneration Flex. remunerationyes ----

38/12 Incentive Patterns and Their Representatives Pattern Characteristics CollectivesCommunities Barter Trade Bearer Banking Bank Notes Bills Rolesasymmetricsymmetricasymmetric Remu- neration Type none reputation service in return notebillcheckbanknote Storage Siteconsumer−provider/bearer Remu- neration Granularity none arbitraryservice fraction of service arbitrarybanknote Assess- ment consumer provider/ consumer provider/bearermarket Copes with Selfishness + − ++ Lavishness++o+ Venial non- cooperation o−−o Trust Trustedconsumernonecons. cons./ debtor cons./ bank (cons./) centr. auth. Anonymity−+−(−)(−)o+ Scalability− −+o+++ Existing approaches various (mil., corp., sens.,priv.) RPG,CORE, Watchdog, Confidant none APE, Ter- miNodes, Sprite none

39/12 Conclusion Summary cooperation beyond autonomy borders requires stimulation cooperation of protocol entities on different layers taxonomy and exemplification of uncooperative behavior discussion of incentive schemes trust transactions remuneration classification of existing approaches for ad hoc networks account vs. reputation based Future work incentive scheme for the discovery and application layer analysis of suitable remuneration types integration of incentive schemes