Rational Diophantine sextuples containing two regular quadruples and one regular quintuple

Abstract: A set of $m$ distinct nonzero rationals ${a_1,a_2,\ldots,a_m}$ such that $a_ia_j+1$ is a perfect square for all $1\leq i<j\leq m$, is called a rational Diophantine $m$-tuple. It is proved recently that there are infinitely many rational Diophantine sextuples. In this paper, we construct infinite families of rational Diophantine sextuples with special structure, namely the sextuples containing quadruples and quintuples of certain type.