Complex sentence: The Tigers have been recognized as a co-national champion by the National Championship Foundation; however, LSU does not officially recognize this season as a national championship season and it was clouded by accusations of professionalism from rival school Tulane which was also undefeated in conference play.
Split into simpler sentences: The Tigers have been recognized as a co-national champion by the National Championship Foundation; however, LSU does not officially recognize this season as a national championship season. It was clouded by accusations of professionalism from rival school Tulane, who was also undefeated in conference play.