Composite Trust Composite Trust Composite Trust A formal - PowerPoint PPT Presentation

Composite Trust Composite Trust Composite Trust A formal derivation of conjunction A formal derivation of conjunction A formal derivation of conjunction and disjunction of trust opinions. and disjunction of trust opinions. and disjunction of trust opinions. Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 1 1

Motivating Example Motivating Example Motivating Example Motivating Example • Trust opinion on a seller B : • Trust opinion on a seller B : Trust opinion on a seller : – Based on 5 successful and 1 failed transactions. – Based on 5 successful and 1 failed transactions. • Trust opinion on a delivery agency C : • Trust opinion on a delivery agency C : Trust opinion on a delivery agency : – Based on 4 successful and 2 failed transactions. – Based on 4 successful and 2 failed transactions. • User contemplates a purchase from B via C . • User contemplates a purchase from B via C . User contemplates a purchase from via . – Succeeds iff B and C individually succeed. – Succeeds iff B and C individually succeed. Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 2 2

Motivating Example Motivating Example Motivating Example Motivating Example • Trust opinion on a seller B : • Trust opinion on a seller B : Trust opinion on a seller : – Based on 5 successful and 1 failed transactions. – Based on 5 successful and 1 failed transactions. • Trust opinion on a delivery agency C : • Trust opinion on a delivery agency C : Trust opinion on a delivery agency : – Based on 4 successful and 2 failed transactions. – Based on 4 successful and 2 failed transactions. • User contemplates a purchase from B via C . • User contemplates a purchase from B via C . User contemplates a purchase from via . – Succeeds iff B and C individually succeed. – Succeeds iff B and C individually succeed. • What is the trust opinion on B  C ? • What is the trust opinion on B  C ? What is the trust opinion on  ? – 9 successes and 3 failures? – 9 successes and 3 failures? Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 2 2

Motivating Example Motivating Example Motivating Example Motivating Example • Trust opinion on a seller B : • Trust opinion on a seller B : Trust opinion on a seller : – Based on 5 successful and 1 failed transactions. – Based on 5 successful and 1 failed transactions. • Trust opinion on a delivery agency C : • Trust opinion on a delivery agency C : Trust opinion on a delivery agency : – Based on 4 successful and 2 failed transactions. – Based on 4 successful and 2 failed transactions. • User contemplates a purchase from B via C . • User contemplates a purchase from B via C . User contemplates a purchase from via . – Succeeds iff B and C individually succeed. – Succeeds iff B and C individually succeed. • What is the trust opinion on B  C ? • What is the trust opinion on B  C ? What is the trust opinion on  ? – 4 successes and 2 failures? – 4 successes and 2 failures? Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 2 2

Motivating Example Motivating Example Motivating Example Motivating Example • Trust opinion on a seller B : • Trust opinion on a seller B : Trust opinion on a seller : – Based on 5 successful and 1 failed transactions. – Based on 5 successful and 1 failed transactions. • Trust opinion on a delivery agency C : • Trust opinion on a delivery agency C : Trust opinion on a delivery agency : – Based on 4 successful and 2 failed transactions. – Based on 4 successful and 2 failed transactions. • User contemplates a purchase from B via C . • User contemplates a purchase from B via C . User contemplates a purchase from via . – Succeeds iff B and C individually succeed. – Succeeds iff B and C individually succeed. • What is the trust opinion on B  C ? • What is the trust opinion on B  C ? What is the trust opinion on  ? – Is a trust opinion even s successes and f failures? – Is a trust opinion even s successes and f failures? Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 2 2

Motivating Example Motivating Example Motivating Example Motivating Example Simple trust opinion Simple trust opinion • Trust opinion on a seller B : • Trust opinion on a seller B : Trust opinion on a seller : – Based on 5 successful and 1 failed transactions. – Based on 5 successful and 1 failed transactions. • Trust opinion on a delivery agency C : • Trust opinion on a delivery agency C : Trust opinion on a delivery agency : – Based on 4 successful and 2 failed transactions. – Based on 4 successful and 2 failed transactions. • User contemplates a purchase from B via C . • User contemplates a purchase from B via C . User contemplates a purchase from via . – Succeeds iff B and C individually succeed. – Succeeds iff B and C individually succeed. • What is the trust opinion on B  C ? • What is the trust opinion on B  C ? What is the trust opinion on  ? – Is a trust opinion even s successes and f failures? – Is a trust opinion even s successes and f failures? Composite trust opinion Composite trust opinion Composite trust opinion Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 2 2

Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability • Targets have an unknown integrity parameter. • Targets have an unknown integrity parameter. Targets have an unknown integrity parameter. – The subject estimates integrity. – The subject estimates integrity. • Subject constructs a probability density • Subject constructs a probability density Subject constructs a probability density function over targets integrity. function over targets integrity. function over targets integrity. – Using knowledge of subject – Using knowledge of subject – Using knowledge of subject Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 3 3

Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability • Targets have an unknown integrity parameter. • Targets have an unknown integrity parameter. Targets have an unknown integrity parameter. – The subject estimates integrity. – The subject estimates integrity. • Subject constructs a probability density • Subject constructs a probability density Subject constructs a probability density function over targets integrity. function over targets integrity. function over targets integrity. – Using knowledge of subject – Using knowledge of subject – Using knowledge of subject nsity ity density obability densi obability de obability de Probabil Probabil Integrity parameter Integrity parameter Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 3 3

Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability Trust Opinions and Probability • Targets have an unknown integrity parameter. • Targets have an unknown integrity parameter. Targets have an unknown integrity parameter. – The subject estimates integrity. – The subject estimates integrity. • Subject constructs a probability density • Subject constructs a probability density Subject constructs a probability density function over targets integrity. function over targets integrity. function over targets integrity. Trust opinions Trust opinions – Using knowledge of subject – Using knowledge of subject – Using knowledge of subject Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 3 3

Assumptions on Simple Trust Opinions Assumptions on Simple Trust Opinions Assumptions on Simple Trust Opinions Assumptions on Simple Trust Opinions I. I. I. No prior knowledge about integrity of agents. No prior knowledge about integrity of agents. No prior knowledge about integrity of agents. II. Probability of success is (solely) determined by II. Probability of success is (solely) determined by II. Probability of success is (solely) determined by the integrity parameter. the integrity parameter. III. Outcomes in past interactions are (solely) III. Outcomes in past interactions are (solely) determined by the integrity parameter. determined by the integrity parameter. determined by the integrity parameter. IV. Unrelated events have no connection. IV. Unrelated events have no connection. IV. Unrelated events have no connection. Composite Trust Composite Trust Tim Muller and Patrick Schweitzer Tim Muller and Patrick Schweitzer 4 4