Machine learning techniques to select Be star candidates - An application in the OGLE-IV Gaia south ecliptic pole fieldM. F. Pérez-Ortiz, A. García-Varela, A. J. Quiroz, B. E. Sabogal and J. HernándezA&A, 605 (2017) A123DOI: https://doi.org/10.1051/0004-6361/201628937