  There exists a wide set of techniques to perform keyword-based search over
relational databases but all of them match the keywords in the users' queries
to elements of the databases to be queried as first step. The matching process
is a time-consuming and complex task. So, improving the performance of this
task is a key issue to improve the keyword based search on relational data
sources.In this work, we show how to model the matching process on
keyword-based search on relational databases by means of the symmetric group.
Besides, how this approach reduces the search space is explained in detail.
