  Satisfiability is a classic problem in computational complexity theory, in
which one wishes to determine whether an assignment of values to a collection
of Boolean variables exists in which all of a collection of clauses composed of
logical OR's of these variables is true. Here, a renormalization group
transformation is constructed and used to relate the properties of
satisfiability problems with different numbers of variables in each clause. The
transformation yields new insight into phase transitions delineating "hard" and
"easy" satisfiability problems.
