1 Correction To: RACSAM (2020) 114:130 https://doi.org/10.1007/s13398-020-00861-z

In the proof of Theorem 9 it is tacitly assumed that p is not in the closure of \(S_x\), whenever \(x \ne p\). This is not necessarily true, but it can be arranged because the space is Hausdorff. To correct the proof, just insert the following line after the period on Page 5, Line 9: Moreover, if \(x \ne p\) we can assume that \(p \notin \overline{S_x}\).