  This paper studies the capacity of a class of discrete memoryless
interference channels where interference is defined analogous to that of
Gaussian interference channel with one-sided weak interference. The sum-rate
capacity of this class of channels is determined. As with the Gaussian case,
the sum-rate capacity is achieved by letting the transceiver pair subject to
interference communicate at a rate such that its message can be decoded at the
unintended receiver using single user detection. It is also established that
this class of discrete memoryless interference channels is equivalent in
capacity region to certain degraded interference channels. This allows the
construction of capacity outer-bounds using the capacity regions of associated
degraded broadcast channels. The same technique is then used to determine the
sum-rate capacity of discrete memoryless interference channels with mixed
interference as defined in the paper. The obtained capacity bounds and sum-rate
capacities are used to resolve the capacities of several new discrete
memoryless interference channels.
