In tiis paper I shall suggest that a study of belief revision in Baduk could be an unexpectedly fertile ground of research for logicians, philosophers, computer scientists, and game theorists as well as for Baduk players. The study of belief revision turns out to be one of the most distinguished success stories in the recent history of logic. Starting from the legendary AGM postulates published in 1985, it has expanded its scope far beyond epistemic logic and philosophy of science up to computer science, artificial intelligence researches, and economics. Nevertheless, there are many serious open problems, which are largely philosophical in character, in current theories of belief revision. By examining some typical situations of belief revision in Baduck, I propose to shed light on one of those philosophical problems, i.e, the principle of informational economy in AGM theory.