On the inner and outer bounds for 2-receiver discrete memoryless broadcast channels

We study the best known general inner bound (K. Marton, January, 2003) and outer bound (C. Nair et al., January, 2007) for the capacity region of the two user discrete memory less channel.We prove that a seemingly stronger outer bound is identical to a weaker form of the outer bound that was also presented in (C. Nair et al., January, 2007). We are able to further express the best outer bound in a form that is computable, i.e. there are bounds on the cardinalities of the auxiliary random variables. The inner and outer bounds coincide for all channels for which the capacity region is known and it is not known whether the regions described by these bounds are same or different. We present a channel, where assuming a certain conjecture backed by simulations and partial theoretical results, one can show that the bounds are different.