The Maine State Ballet will present its full-length premiere of the classic ballet “Swan Lake” May 20-21 at Merrill Auditorium in Portland. “Swan Lake” tells the tale of beautiful young queen Odette, who is transformed into a swan by the evil sorcerer, Count VonRothbart. Set to music by Peter Tchaikovsky, “Swan Lake” will be performed at 7 p.m. Saturday, May 20, and at 1 p.m. Sunday, May 21. Tickets, $15-$35, are on sale through PortTix, 842-0800, or www.porttix.com. For more information, call 781-7672, or visit www.mainestateballet.org.