Non-deterministic computations greatly enhance the
expressive power of functional logic programs, but are
often computationally expensive.
We analyze two programming techniques that improve the
time and memory efficiency of some non-deterministic computations.
These techniques rely on the introduction of a new symbol
into the signature of a program.
In one technique this symbol is a polymorphic defined operation,
in the other an overloaded constructor.
Our programming techniques may save
execution time by reducing the number of steps of a computation,
as well as memory occupation, by reducing the number of terms constructed
by a computation.
We show how to apply our techniques using some examples,
and informally reason about their effects.