  Using an analytical variational approach we calculate the hole-hole contact
interaction on the N\'{e}el background. Solution of the Bethe-Salpeter equation
with this interaction gives bound states in $d$- and p-waves with binding
energies close to those obtained by numerical methods. At $t/J \ge 2-3$ the
bound state disappears. In conclusion we discuss the relation between short
range and long range interactions and analogy with the problem of pion
condensation in nuclear matter.
