In this paper, the concept of a new ?-generalized quasi metric space is
introduced. A number of well-known quasi metric spaces are retrieved from
?-generalized quasi metric space. Some general fixed point theorems in a
?-generalized quasi metric spaces are proved, which generalize, modify and
unify some existing fixed point theorems in the literature. We also give
applications of our results to obtain fixed points for contraction mappings
in the domain of words and to prove the existence of periodic solutions of
delay differential equations.
Existence of periodic solutions for a class of damped vibration problems