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September 15, 2008

Day 1 on CA

I am thinking about writing a paper to model the growth of Wal-mart stores and distribution centers by cellular automata. The location data of wal-mart stores and DCs are downloaded from Prof. Thomas Holmes' website.

CA is a technique modeling microscopic behaviors. The birth of this concept dates back to 1970s, and has received increasing attention in research on complex systems.

According to Jacob Goldenberg in his paper "Riding the Saddle: How Cross-Market Communications can Create a Major Slump in Sales", CA has the following features:

- The CA approach can uncover the complexity of the microscopic behaviors to help us understand better the underlying mechanisms of a system.

- CA modeling requires a reliable micro-representation of the relations among individuals.

- When a phenomenon is monotonic or linear in most of its duration, aggregate-level modeling may be more convenient to employ. Yet for a nonlinear or monotonic regime, it is probably better to adopt CA technique.

An interesting youtube movie on the diffusion of wal-mart.

Some questions to think about:
a. What is the economic/geographical relationship between stores and DCs?
b. What kind of rules should wal-mart have in terms opening new stores and DCs?
c. What are the managerial policy implications from this geographical distribution?

Related papers:

Back, T. et al. 1998. Modeling urban growth by cellular automata
Besussi E. 1998 The diffused city of the Italian North-east identification of urban dynamics using cellular automata urban models. Comput. Enviorn. & Urban Systems. vol. 22. No. 5. pp. 497-523

September 12, 2008

Bilical social network

An interesting visualization of cross-references of names and locations in the Bible text performed by Chris Harrison, a graduate student at CMU. As can be seen, Israel, Judah, Jerusalem, and David are the nodes with the largest number of degrees.

It would be of further interest to look at which chapters they are from and how they are connected.

BibleNetworksmall.jpg
(Source: http://www.chrisharrison.net/projects/bibleviz/index.html)

September 11, 2008

About author and the blog

A native of China, Arthur Huang is a Phd student of transportation and urban economics at the Univeristy of Minnesota, Twin Cities. My research interest lies in the broad domain of complex systems from a microscopic perspective. My current research focus is on urban clusters, transportation networks, and firms' location choice on supply chains networks.

I will use this blog to record my recent thinkings and readings on urban economics and complex systems.

Your comments are welcome.