G. K. SURYA PRAKASH, PhD, is Professor of Chemistry at the University of Southern California at Los Angeles, California. His primary research interests are in the area of carbocation, superacid, hydrocarbon, and synthetic organic chemistry. He has published more than 280 scientific papers in the field and has coauthored and edited three books. PAUL v. R. SCHLEYER, PhD, is Professor of Chemistry at the University of Erlangen-Nurnberg, Erlangen, Germany. His main research interests are in the area of mechanistic, structural, and computational chemistry. He pioneered the applications of theory to intriguing chemical problems. He is highly prolific with more than 800 scientific publications to his credit and has coauthored or edited more than 10 monographs.