Despite being continents apart, Berlin and Tokyo have much to learn from each other, Berlin Mayor Eberhard Diepgen said on a recent trip to Tokyo.In an interview with The Japan Times, Diepgen said he expects the Berlin-Tokyo relationship, unofficially established in 1985 and later formalized in a friendship agreement in May 1994, will continue to strengthen, especially regarding economic ties.One example of deeper cooperation was an agreement signed Oct. 7 that will allow Berlin to use Tokyo-developed technology to lay fiber optic cable within the city sewer infrastructure, Diepgen said.His visit to Tokyo and meeting with Gov. Yukio Aoshima is the most recent in a series of meetings since the signing of the 1994 agreement. In addition to talking with the governor, Diepgen spoke at a symposium dealing with city planning and the image of Berlin, among other things. "Berlin is the city in the west nearest to the east in Europe," Diepgen said, making it uniquely suited to grow economically with the opening of Eastern Europe. One example is the Potsdamer Platz, currently under construction in Berlin, and destined to be the site of Sony's European headquarters, Diepgen said.Beyond economics, Tokyo and Berlin have many similar problems, he said. They can profit from sharing information about their experiences and solutions, especially in areas concerning the environment, garbage disposal and traffic control.