Definition.
Orthogonality. If a,b,c are real, or one is real and the other two
are complex conjugates, and 
, then we have the following
orthogonality relation
where
with
and
If a > 1 and b and c are real or complex conjugates,
and the pairwise products of a,b and c have
absolute value less than one, then we have another orthogonality relation
given by :
where 
and 
are as before,
and
Recurrence relation.
where
and
Normalized recurrence relation.
where
q-Difference equation.
where
If we define
then the q-difference equation can also be written in the form
where
Forward shift operator.
or equivalently
Backward shift operator.
or equivalently
Rodrigues-type formula.
Generating functions.
