 Complete the following phrase:  In 2011 the event returned to the Barbican Centre in York, and the matches until the quarter-finals were reduced to best of 11 frames. In 2013 a 128-player flat draw was used, with all players starting in the first round and all rounds played at the Barbican venue. The tournament was contractually due to stay at the Barbican Centre until 2013, but it also hosted the event in 