Yuji Murayama is a professor of spatial information science, University of Tsukuba, Japan. He is a Member of the Science Council of Japan and Director of the Tokyo Geographical Society, Japan. His research interests are geographical information science, spatial analysis, and urban/transport geography. He served as President of the GIS Association (2006–2008), Editor-in-Chief of the Theory and Applications of GIS (2004–2006), Editor-in-Chief of the Geographical Review of Japan, Ser.B (2006–2008), and Steering Committee Member of the IGU Urban Commission (2000–2008). Professor Murayama is now Editor-in-Chief of Tsukuba Geoenvironmental Sciences (2013–Present), Editor of Urban Studies Research (2010–Present), Editorial Manager of AJG Library: International Perspectives in Geography (2013–Present), Associate Editor of Euro-Mediterranean Journal of Environmental Integration (2015-present), and Steering Committee Member of IGU Transport Geography Commission (2008–Present).
He is also on the editorial boards of several international academic journals including GeoJournal (2000–Present), Urban Geography (2002–2012), Journal of Transport Geography (2004–Present), Positioning (2012–Present), Transactions in GIS (2013–Present), Progress in Earth and Planetary Science (2013–Present), Open Journal of Remote Sensing and Positioning (2013–Present), and Computers, Environment and Urban Systems (2015–Present).
Using the city-system concept, this study tries to measure the degree of interdependency between cities in the international city-system and how it has changed over time. A city-system is a geographical term referring to an aggregate of sets of cities interrelated. Cities are interdependent in such a way that any significant change in economic activity, occupational structure, total income or population of one member city will directly bring about some modification of the other set members. This study regards Japan, the U.S. and Canada as one unit of an international city-system. These three countries are highly interrelated with each other in the international city-system.