Tickets are available beginning today to see Arianna Huffington, president and editor-in-chief of the Internet newspaper The Huffington Post, speak at Eisenhower Auditorium next week. The Cambridge graduate and political activist is the author of thirteen books and the host of her own national syndicated public radio program, “Both Sides Now,” where she discusses political issues from multiple angles along with former white house aide Mary Matalin. Find out when and where you can get tickets.