12
Mar

SYNTHESE Journal paper: Action Emulation

Title: Action Emulation

Authors: Jan van Eijck, Ji Ruan & Tomasz Sadzik

Abstract:
The effects of public announcements, private communications, deceptive messages to groups, and so on, can all be captured by a general mechanism of updating multi-agent models with update action models, now in widespread use. There is a natural extension of the definition of a bisimulation to action models. Surely enough, updating with bisimilar action models gives the same result (modulo bisimulation). But the converse turns out to be false: update models may have the same update effects without being bisimilar. We propose action emulation as a notion of equivalence more appropriate for action models, and generalizing standard bisimulation. It is proved that action emulation provides a full characterization of update effect. We first concentrate on the general case, and next focus on the important case of action models with propositional preconditions. Our notion of action emulation yields a simplification procedure for action models, and it gives designers of multi-agent systems a useful tool for comparing different ways of representing a particular communicative action.

Published in the Journal of Synthese: Volume 185, Issue 1 (2012), Page 131-151.

Acknowledgements: 

We thank Johan van Benthem, Hans van Ditmarsch, Floor Sietsma, Albert Visser and Yanjing Wang for inspiring discussions, and thank five anonymous reviewers for helpful comments. We are grateful to our editor Wiebe van der Hoek for encouragement, patience, trust and flexibility. The first author is grateful to the Netherlands Institute for Advanced Studies in Wassenaar (NIAS) for providing the opportunity to work on this paper as Fellow-in-Residence.

Bibtex:

@article{AEvanEijckRuanSadzik:2012,
Author = {Jan van Eijck and Ji Ruan and Tomasz Sadzik},
Journal = {Synthese},
Number = {1 (2012)},
Pages = {131-151},
Title = {Action Emulation},
Volume = {185},
Year = {2012}}

29
Sep

Johan’s Lecture in Beida

I was fortunate to attend Prof. Johan van Benthem’s lecture on logic dynamics in Beida. He was one of my master thesis supervisor back in 2004, and we last met was in Liverpool in March 2009 on occasion of celebrating Wiebe’s 50th Birthday. I am a big fan of him as he has set a great example of how a researcher can be. Here are some Photos. A video clip will appear later.

Johan Lecture on Logic Dynamics

Johan Lecture on Logic Dynamics (more…)

21
Sep

我将在北大的学术报告:通用游戏竞赛的逻辑 (星期天 25-09-2011)

题目:通用游戏竞赛的逻辑 (Logic for General Game Playing)

主讲人:阮吉
计算机科学和工程学院,新南威尔士大学,澳大利亚

时间:九月二十五日,星期天,晚上8点
地点:哲学系1层会议室

摘要:通用游戏竞赛GGP(General Game Playing)的目标是创建能自主地学习游戏规则进行游戏比赛的通用智能系统。和1997年打败人类国际象棋冠军的深蓝系统不同的是,通用游戏系统的设计者事先不知道竞赛的具体游戏,而只是被告知所有游戏是用游戏描述语言GDL(Game Description Language)所描述。GDL是一种基于规则的逻辑编程语言。自从2005年通用游戏竞赛在国际人工智能会议AAAI举办以来,已经引起了广泛的兴趣和深入的研究。GDL本身也从只能描述完全信息游戏(例如象棋)扩展到也能描述非完全信息游戏(例如扑克)。我将首先介绍如何对游戏进行描述,然后深入讨论逻辑在游戏推理和刻画中的应用,并展示一些推理复杂性结果。

http://www.phil.pku.edu.cn/cllct/ann_content.php?msgid=215

更新:现场的照片

Ji Ruan at PKU

例子
Ji Ruan at PKU

提问
Ji Ruan at PKU

来自相册:
http://www.flickr.com/photos/jiruan/sets/72157627656865185

20
Sep

My coming up seminar at Tsinghua University (Friday 23-09-2011)

Date: Friday, 23 September, 2011
Location: 清华新斋335

1:30-3:30 PM
Speaker: Patrick Girard
Department of Philosophy, The University of Auckland

Title: Logic in the Communities

Photo Update:

Patrick Girard at Tsinghua

3:30- 5:30 PM
Speaker: Ji Ruan
School of Computer Science and Engineering, The University of New South Wales

Title: A Logic for Knowledge Flow in Social Networks (社交网络中的知识流的逻辑)

Abstract: In this talk, I will present a formal framework for analysing the flow of information and knowledge through social networks. More specifically, we propose a multi-agent epistemic logic in which we can represent and reason about communicative actions based on social networks and the resulting knowledge and ignorance of agents. This logic is applied to formally analyse the “Revolt or Stay-at-home” problem where social networks play an important role in agents’ knowledge acquisition and decision-making. We evaluate our work by proving some mathematical properties of our new logic, including the fact that it generalises the existing Logic of Public Announcement. (This is a joint work with Prof. Michael Thielscher)

Reference Link.

Photo Update:
Ji Ruan at Tsinghua

Ji Ruan at Tsinghua

More photos:
http://www.flickr.com/photos/jiruan/sets/72157627753995408/

12
Sep

Conference paper: A Logic for Knowledge Flow in Social Networks

Title: A Logic for Knowledge Flow in Social Networks

Authors: Ji Ruan and Michael Thielscher
School of Computer Science and Engineering, The University of New South Wales, Australia

Abstract: In this paper, we develop a formal framework for analysing the flow of information and knowledge through social networks. More specifically, we propose a multi-agent epistemic logic in which we can represent and reason about communicative actions based on social networks and the resulting knowledge and ignorance of agents. This logic is applied to formally analyse the “Revolt or Stay-at-home” problem where social networks play an important role in agents’ knowledge acquisition and decision-making. We evaluate our work by proving some mathematical properties of our new logic, including the fact that it generalises the existing Logic of Public Announcement.

Accepted and presented at the 24th Australasian Joint Conference on Artificial Intelligence (AI2011), Perth Australia, December 2011.

Download:

Bibtex: (more…)

05
Sep

Journal paper: Connecting Dynamic Epistemic and Temporal Epistemic Logics

Title: Connecting Dynamic Epistemic and Temporal Epistemic Logics

Authors: H.P. van Ditmarsch, W. van der Hoek, and J. Ruan.

Abstract: We give a relation between a logic of knowledge and change, with a semantics on Kripke models, and a logic of knowledge and time, with a semantics on interpreted systems. In particular, given an epistemic state (pointed Kripke model with equivalence relations) and a formula in a dynamic epistemic logic (a logic describing the consequences of epistemic actions), we construct an interpreted system relative to that epistemic state and that formula that satisfies the translation of the formula into a temporal epistemic logic. The construction involves that the protocol that is implicit in the dynamic epistemic formula, i.e., the set of sequences of actions being executed to evaluate the formula, is made explicit. We first focus on the logic of knowledge and change that is known as public announcement logic, then generalize our results to a dynamic epistemic logic.

It is published in The Logic Journal of the IGPL.
http://jigpal.oxfordjournals.org/content/early/2011/10/27/jigpal.jzr038.refs

PDF:
http://jigpal.oxfordjournals.org/content/early/2011/10/27/jigpal.jzr038.full.pdf+html

Prepublication version.

It is an extended version of this workshop paper.

The paper was first submitted when I was still at the University of Liverpool (UK) in 2009; the revision was made when I was at the StFX University (Canada) in 2010, and finally accepted when I moved to the current University of New South Wales (Australia) in 2011.

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