Saturday 22 September 2007

32, Reaching Agreements Through Argumentation

Notes taken from 'Reaching agreements through argumentation: a logical model and implementation' (1998), Sarit Kraus, Katia Sycara, Amir Evenchik

1, Introduction

2, The Mental Model

Classification of intentions:
- "Intend-to-do", refers to actions within the direct control of the agent.
- "Intend-that", refers to propositions not directly within the agent's realm of control, that the agent must rely on other agents for satisfying.

(The Formal Model, Syntax, Semantics)

Agent Types: Bounded Agent, An Omniscient Agent, A Knowledgeable Agent, An Unforgetful Agent, A Memoryless Agent, A Non-observer, Cooperative Agents

3, Axioms for Argumentation and for Argument Evaluation

The argument types we present (in order of decreasing strength) are:
(1) Threats to produce goal adoption or goal abandonment on the part of the persuadee.
(2) Enticing the persuadee with a promise of a future reward.
(3) Appeal to past reward.
(4) Appeal to precendents as counterexamples to convey to the persuadee a contradiction between what she/he says and past actions.
(5) Appealing to "prevailing practice" to convey to the persuadee that the proposed action will further his/her goals since it has furthered others' goals in the past.
(6) Appeal to self-interest to convince a persuadee that taking this action will enable achievement of a high-importance goal.

"... Agents with different spheres of expertise may need to negotiate with each other for the sake of requesting each others' services. Their expertise is also their bargaining power..."

(Arguments Involving Threats, Evaluation of Threats, Promise of a Future Reward, Appeal to Past Promise, Appeal to "Prevailing Practice", Appeal to Self Interest, Selecting Arguments by an Agent's Type, An Example: Labor Union vs. Management Negotiation, Contract Net Example)

4, Automated Negotiation Agent (ANA)

The general structure of an agent consists of the following main parts:
- Mental state (beliefs, desires, goals, intentions)
- Characteristics (agent type, capabilities, belief verification capabilities)
- Inference rules (mental state update, argument generation, argument selection, request evaluation)

(The Structure of an Agent and its Life Cycle, Inference Rules for Mental State Changes, Argument Production and Evaluation, Argument Selection Rules, Request Evaluation Rules, The Blocks World Environment, Simulation of a Blocks World Scenario)

5, Related Work

(Mental State, Agent Oriented Languages, Multi-agent Planning, Automated Negotiation, Defeasible Reasoning and Computational Dialectics, Game Theory's Models of Negotiation, Social Psychology)

6, Conclusions

Sunday 9 September 2007

31, Customer Coalitions in Electronic Markets

Notes taken from 'Customer Coalitions in Electronic Markets' (2001), by Maksim Tsvetovat, Katia Sycara, Yian Chen, and James Ying

"... In this paper, we report on coalition formation as a means to formation of groups of customers coming together to procure goods at a volume discount ("buying clubs") and economic incentives for creation of such group..."

1, Introduction

A coalition is a set of self-interested agents that agree to cooperate to execute a task or achieve a goal.

2, Prior Work

3, Incentives for Customer Coalitions

(Supplier Incentive to Sell Wholesale; Customer Incentive to Buy Wholesale)

4, Coalitions and Wholesale Purchasing

In the real world, a single customer rarely wants to buy large enough quantities of goods to justify wholesale purchasing... In order to lower the purchase price (and, therefore, increase utility), self-interested customer agents can join in a coalition... This would enable the coalition to buy a wholesale lot from the supplier, break it into sub-lots and distribute them to its members, thus raising the utility of each individual member.

However, the formation and administration of coalitions, as well as distribution of sub-lots has its costs... In particular, such costs include the cost of administering coalition membership, cost of collecting payments from individual memberships, and the cost of distributing items to the members when the transaction is complete. In some cases (such as distributing copies of software) some of the costs can be very small, and in other cases may rise to be prohibitively large.

5, Coalition Models

It is possible to construct a number of coalition models and protocols, all of which would have different properties and requirements. In general, all coalition models include several stages:
- Negotiation
- Coalition Formation
- Leader Election/Voting
- Payment Collection
- Execution/Distribution stage

In design of coalition protocols, the following issues have to be taken into account:
- Coalition Stability
- Distribution of Gain
- Distribution of Costs and Utility
- Distribution of Risk
- Trust and Certification

Most coalition protocols can be divided into two classes (pre-negotiation and post-negotiation), based on the order in which negotiation and coalition forming happen...

(Post-negotiation; Pre-negotiation; Distribution of Costs and Utility)

6, Customer Coalitions for Volume Discounts - An Implementation

(Coalition Protocol; Testbed Architecture; Implementation of Agents; PiPL Language)

7, Conclusions and Future Work

30, Bid Together, Buy Together

Notes taken from 'Bid Together, Buy Together: On the Efficacy of Group-Buying Business Models in Internet-based Selling' (2001), by Robert J. Kauffman and Bin Wang

"... Dynamic pricing approaches are used by many well known Internet-based firms, including firms that offer online auctions such as eBay and A group-buying discount is a dynamic pricing mechanism that mimics the general approach of traditional "discount shopping clubs". Group buying pricing mechanisms permit buyers to aggregate their purchasing power and obtain lower prices than they otherwise would be able to get individually..."

1, Introduction

Model type: Group-buying models
Key concept: Enable buyers to obtain lower prices, as more people indicate a willingness to buy from the Internet-based seller's Web site. There are two variaties, involving group-buying with a fixed time period to completion of an auction, and group-buying with a fixed price that is achieved only when enough buyers participate.

... In a discussion on the recent closure of Mercata, Cook (2001) points out that the group-buying business model is too difficult for the general concumer to understand. The author also argues that the mechanics of group-buying on the Internet also prevent impulse buying, due to the lengthy periods consumers have to wait until until the end of the auction cycles that characterize group-buying market mechanisms. More importantly, he argues that the transaction volume on group-buying sites is much smaller than those of the traditional discount stores, which makes it difficult for group-buying sites to compete with retial giants such as Wal-Mart and Target...

2, The Basics of Group-Buying Models in E-Commerce

2.1, The Market Mechanisms

Pricing to match buyers and sellers is an important function of a market. In the bricks-and-mortar world, posted pricing mechanisms have been the dominant pricing strategies, where retailers display the prices they ask for the merchandise and consumers decide whether they would accept the prices or not. Under dynamic pricing mechanisms, however, buyers are no longer left with this take-it-or-leave-it decision. They can actively negotiate with the sellers to reach a satisfactory price...

2.2, The Value Proposition for Group-Buying on the Internet

The primary value proposition of group-buying business models to consumers is the lower prices they can provide, due to the buyers' collective bargaining power. By accumulating a large number of orders in a short period of time, group-buying Web sites claim they can negotiate low prices with manufacturers and suppliers, and then pass these savings on to their customers...

3, Buyer Behaviour and Market Competition in Group-Buying

(Buyer Behaviour Under the Group-Buying Market Microstructure; The Anticipation of a Price Drop; The Group-Buying Mentality; The Price Threshold Effect; Competition in the Group-Buying Market)

... The "Save-a-Spot" feature at Mobshop allowed shoppers to place conditional bids at lower prices if they were dissatisfied with the current price. The created a win-win situation for both the firm and its customers... Thus, customers did not incur the risk of buying at prices higher than they were willing to pay... And so we see that, under the group-buying market microstructure, consumers have the oppurtunity to collaborate with each other to get lower prices, instead of simply bidding against each other in auctions. Hence, consumers have the incentive to recruit other shoppers...

4, A Framework for Comparing Group-Buying Websites

Based on our survey of the group-buying websites, we identified two primary kinds of customer targeting strategies: business-to-customer (B2C) and business-to-business (B2B). The B2B category also includes the education and government procurement. We also distinguish whether a buyer or a seller initiates the auction cycle... Finally, we note that the demand aggregation approach can be determined by whether the Web site is a destination site or a site with a distributed-service model (e.g. embedded in other Web sites)...

(;;; Other Group-Buying Websites)

5, Analyzing Group-Buying Business Models

Some Dimensions for Comparing Group-Buying Business Models:
- Industry Studies
- How Do Prices on Group-Buying Web Sites Compare With Other Firms' Prices?

Comparing Rivals: Mercata and Mobshop
- Pricing Strategy
- Information Endowment
- Site Features
- Product Emphasis
- Pre-Trade and Post-Trade Logistics

(1) In which market does the group-buying model work best, B2C or B2B?
(2) How should firms that are focusing on the B2C market compete with other business models for limited customer resources?
(3) What do we learn about the composition of effective product offerings at group-buying Web sites?
(4) To what extent are group-buying Web sites at a disadvantage when it comes to the use of shopbots for comparison shopping?

6, Conclusion

Friday 7 September 2007

Group Buying

Taken from 'Performance of software agents in non-transferable payoff group buying' (2006), by Frederick Asselin and Brahim Chaib-Draa

... Group buying is a natural application domain for research on coalition formation in a multi-agent system (MAS). Consumers have an incentive to regroup with the unit price reduction as a function of the number of units bought by the group. However, as more and more consumers become members of the same group, there is an increase in the number of compromises that each consumer must make in order to agree on the product bought by the group...

Tuesday 4 September 2007

Knowledge Representation and Reasoning

"Knowledge representation and reasoning is the area of Artificial Intelligence (AI) concerned with how knowledge can be represented symbolically and manipulated in an automated way by reasoning programs. More informally, it is the part of AI that is concerned with thinking, and how thinking contributes to intelligent behaviour... in the field of knowledge representation and reasoning we focus on the knolwedge, not on the knower..."

Source: 'Knowledge Representation and Reasoning' (2004), Ronald Brachman and Hector Levesque

Monday 3 September 2007

29, Protocol Conformance for Logic-based Agents

'Protocol Conformance for Logic-based Agents' (2003), by Ulrich Endriss, Nicolas Maudet, Fariba Sadri and Francesca Toni

... In non-cooperative interactions (such as negotiation dialogues) occurring in open societies it is crucial that agents are equipped with proper means to check, and possible enforce, conformance to protocols. We identify different levels of conformance (weak, exhaustive, and robust conformance)...

1, Introduction

2, Representing Protocols

(Legality, Expected inputs, Correct responses)

3, Levels of Conformance

(Weak conformance, Exhaustive conformance, Robust conformance)

4, Logic-based Agents

(Checking conformance (Response space), Enforcing conformance, Examples)

5, Conclusion

Saturday 1 September 2007

Supply Chain Library

Taken from 'Modelling Supply Chain Dynamics: A Multiagent Approach' (1998), Jayashankar M. Swaminathan, Stephen F. Smith and Norman M. Sadeh

"We classify different elements in the supply chain library into two broad categories - Structural Elements and Control Elements. Structural elements (modeled as agents) are involved in actual production and transportation of products, and control elements help in coordinating the flow of products in an efficient manner with the use of messages. Structural elements correspond to agents and control elements correspond to the control policies in our framework. Structural and Control elements are further classified as follows:

Structural Elements
- Production (Retailer, Distributor, Manufacturer, Supplier)
- Transportation (Vehicles)

Control Elements
- Flow (Loading, Routing)
- Inventory (Centralized, Decentralized)
- Demand (Forecast, Marketing)
- Supply (Contracts)
- Information (Real-time, Periodic)

As well as the above, there is also the Customer.