  We perform a thorough phase-plane analysis of the flow defined by the
equations of motion of a FRW universe filled with a tachyonic fluid plus a
barotropic one. The tachyon potential is assumed to be of inverse square form,
thus allowing for a two-dimensional autonomous system of equations. The
Friedmann constraint, combined with a convenient choice of coordinates, renders
the physical state compact. We find the fixed-point solutions, and discuss
whether they represent attractors or not. The way the two fluids contribute at
late-times to the fractional energy density depends on how fast the barotropic
fluid redshifts. If it does it fast enough, the tachyonic fluid takes over at
late times, but if the opposite happens, the situation will not be completely
dominated by the barotropic fluid; instead there will be a residual
non-negligible contribution from the tachyon subject to restrictions coming
from nucleosynthesis.
