  The focus is on noise-free half-duplex line networks with two sources where
the first node and either the second node or the second-last node in the
cascade act as sources. In both cases, we establish the capacity region of
rates at which both sources can transmit independent information to a common
sink. The achievability scheme presented for the first case is constructive
while the achievability scheme for the second case is based on a random coding
argument.
