  The (2+p)-Satisfiability (SAT) problem interpolates between different classes
of complexity theory and is believed to be of basic interest in understanding
the onset of typical case complexity in random combinatorics. In this paper, a
tricritical point in the phase diagram of the random $2+p$-SAT problem is
analytically computed using the replica approach and found to lie in the range
$2/5 \le p_0 \le 0.416$. These bounds on $p_0$ are in agreement with previous
numerical simulations and rigorous results.
