In this paper, we derive a bound of the fourth Hankel determinant for the class of star-like functions. We also consider this problem for 2-fold and 3 -fold symmetric star-like functions. In this case, we obtain sharp results.

The purpose of this paper is to introduce and study some of the properties of supra N-open sets via supra N-derived, supra N-border, supra Nfrontier and supra N-exterior. Also we introduce some separation axioms using supra N-open set.