The Mathematician Presents Any idiot can get a PhD in mathematics. All it takes is time and talent, a little want-to. Add to these an exhausted impatience and there you have him: Daniil Roitman. He’d come stateside for a postdoc at Columbia University, pale, often unshaven, balding with watery black eyes. It was the research that excited him, but one of the conditions of his studies was that he teach. Thus three mornings a week he entered the amphitheater, stood at the podi