Let R be a binary relation and let a , b be sets. There exists a reduction sequence p w.r.t. Let R be a binary relation and let a , b be sets. We say that a and b are convertible w.r.t.
R R reduces a to b .
For every binary relation R and for every set a holds R reduces a to a . Let R be a binary relation and a , b , c be sets. Suppose R reduces a to b and R reduces b to c . Then R reduces a to c . Let R be a binary relation, p be a reduction sequence w.r.t.