Anne Hidalgo, the mayor of Paris, is usually credited for it. It works in Paris because the official boundary is quite small compared to other cities, about 100km^2 containing 2 million people, whereas in Berlin the equivalent is almost 900km^2 and 3.5 million people. So the population that vote for her are almost exclusively urban dwellers whereas in Berlin the mayor has to appease suburbanites too.
Anne Hidalgo, the mayor of Paris, is usually credited for it. It works in Paris because the official boundary is quite small compared to other cities, about 100km^2 containing 2 million people, whereas in Berlin the equivalent is almost 900km^2 and 3.5 million people. So the population that vote for her are almost exclusively urban dwellers whereas in Berlin the mayor has to appease suburbanites too.