28
May

StFX Logic Talk 1: Solving Sum-and-Product Riddle Using Public Announcement Logic

I plan to give four talks about my research, in the Center for Logic and Information. The first two will be kept more introductory, and the remaining two will be more advanced. Here is my first talk given on last Friday.

Solving Sum-and-Product Riddle Using Public Announcement Logic

Abstract:

In this talk I will present a joint work with H. van Ditmarsch and R. Verbrugge. I will first introduce the problem we want to solve: the Sum-and-Product Riddle. Then I will present how to model the Sum-and-Product riddle in a modal logic called public announcement logic. This logic contains operators for knowledge, but also operators for the informational consequences of public announcements. The logic is interpreted on multi-agent Kripke models. The riddle is then implemented and its solution verified in the epistemic model checker DEMO. The results are compared with other work in epistemic model checking and the complexity is experimentally investigated for several representations and parameter settings.

Here is the Sum-and-Product Riddle:

Adam says to S and P: I have chosen two integers x, y such that 1 < x < y and x + y ≤ 100. In a moment, I will inform S only of s = x + y, and P only of p = xy. These announcements remain private. You are required to determine the pair (x, y).

He acts as said. The following conversation now takes place:
i. P says: ‘I do not know it.’
ii. S says: ‘I knew you didn’t.’
iii. P says: ‘I now know it.’
iv. S says: ‘I now also know it.’

Determine the pair (x,y).

Reference:
H.P. van Ditmarsch, J. Ruan, L.C. Verbrugge, Sum and Product in Dynamic Epistemic Logic.

21
May

A sudden warm day



A sudden warm day, originally uploaded by jiruan.

We got 26 degrees today in Antigonish.

It is strange that we suddenly have such a warm day. But it is nicely warm and I like it.

I was waring a sweater when I go to my office in the morning. Now I have through it away.

12
May

My PhD Thesis

This is a dedicated page of my PhD thesis:

Reasoning about Time, Action and Knowledge in Multi-Agent Systems

07
May

Suggestions to the webmaster of loriweb.org

As a former student of the ILLC, I am very happy to see that the ILLC has launched a blog-based webportal for the research community of logic and rational interactions, called loriweb.org. Here is a snapshot:

loriweb.org

The ILLC has finally made an attempt going from web1.0 to web2.0, which means more dynamics and interactions!

However, I noticed that there is an important element missing on loriweb’s front page. It is a link to the RSS feed. What is RSS?

RSS (Rich Site Summary) is a format for delivering regularly changing web content. Many news-related sites, weblogs and other online publishers syndicate their content as an RSS Feed to whoever wants it.

More details of RSS: http://en.wikipedia.org/wiki/RSS_(file_format)

Why RSS is important?

RSS solves a problem for people who regularly use the web. It allows you to easily stay informed by retrieving the latest content from the sites you are interested in. You save time by not needing to visit each site individually. You ensure your privacy, by not needing to join each site’s email newsletter. The number of sites offering RSS feeds is growing rapidly and includes big names like Yahoo News.

Actually, since the loriweb is using the popular wordpress software (good choice!), it has an RSS feed by default: http://loriweb.org/?feed=rss2. So I subscribed to it using my Google RSS Reader. But then I found this problem. The loriweb RSS feed only outputs an abstract of the content. For example, here is a snapshot of the loriweb in my Google Reader:

lori-rss-abstract

You have to click on the article in order to read it fully.

And this is what you see from the blog of Terence Tao, a well-regarded mathematician:

tao-rss-fulltext

In this case I can read all his articles without leaving the my reader. The difference is small if you only subscribe to a few blogs, but very noticeable when you
subscribe to dozens of blogs, which may have 1000+ new articles every week.

So my suggestions to the webmaster of loriweb.org are as follows:

  • add a link to the RSS feed in the front page
  • output the full text in the RSS feed.
    It is very easy to set in wordpress: login as admin, and find the Settings section, and choose the Reading subsection, then you can see the following:  just make sure Full text is chosen (this view is based on version 2.7.1)
    wordpress set full text

Cheers, Ji

01
May

WoW, Whitehouse 2.0!

The USA White House launched its strategy to reform the government in the Web 2.0 age. In this post:
http://www.whitehouse.gov/blog/09/05/01/WhiteHouse/, it gives the information channels through which white house is reaching its citizens. These channels include:

  • Whitehouse.gov
  • Facebook.com/WhiteHouse
  • MySpace.com/WhiteHouse
  • Twitter.com/WhiteHouse
  • Flickr.com/WhiteHouse
  • Vimeo.com/WhiteHouse
  • YouTube.com/WhiteHouse
  • iTunes (videos & podcasts)

I would say this government is leading toward the right way. Well, my government, the Chinese government, is still using a communist version of web 1.0 tools. You see, my blog is still blocked from China Mainland. What a shame.

05
Apr

Why did the global economic crisis happen?

An explanation from a South Park Episode is available here. Highly recommended.

If the above link does not work, google these words:
South Park: Season 13 Episode 3 – “Margaritaville”

My original source is this.

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