| In the paper "On sum theorems for M1-spaces" , the author introduced the concept of strongly hereditarily closure-preserving family , and proved that "M1-spaces satisfy the a- hereditarily closure-preserving open sum theorem" , so , normality of Theorem 3 in was not essential. In this note we show that "strongly hereditarily closure-preserving family" is equivalent to "hereditarily closure-preserving family", and that conclusion of Theorem 3 in [1] is incorrect and normality of Theorem 3 in [3] in essential. |
