  We consider Achlioptas processes for k-SAT formulas. We create a semi-random
formula with n variables and m clauses, where each clause is a choice, made
on-line, between two or more uniformly random clauses. Our goal is to delay the
satisfiability/unsatisfiability transition, keeping the formula satisfiable up
to densities m/n beyond the satisfiability threshold alpha_k for random k-SAT.
We show that three choices suffice to raise the threshold for any k >= 3, and
that two choices suffice for all 3 <= k <= 25. We also show that two choices
suffice to lower the threshold for all k >= 3, making the formula unsatisfiable
at a density below alpha_k.
