Complex sentence: In November 1999, Barnés resigned of his position as rector of the UNAM after giving in to demands of the CGH who kept extending the strike and imposing new demands.
Split into simpler sentences: In November 1999, Barnés resigned his position as rector of the UNAM. He had given in to some of the demands of the CGH; the CGH, however, kept extending the strike and making new demands.