IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 46, NO. 4, JULY 2000 Rudolf Ahlswede, Ning Cai, Shuo-Yen Robert Li, Senior Member, IEEE, andRaymond W. Yeung, Senior Member, IEEE Abstract—We introduce a new class of problems called networkinformation flow which is inspired by computer network applications.Consider a point-to-point communication network on whicha number of information sources are to be mulitcast to certain setsof destinations. We assume that the information sources are mutuall ...