Too young, too far, too fast? Ruth Lawrence, probably the best-known young university entrant, now has a year-long research and teaching post at Givat Ram University in Jerusalem. It is the first time she has been separated from her father, who was at her side throughout her years at Oxford University. Aged 13, she took a first-class honours degree in mathematics. Now 26, she is a professor at the University of Michigan, where she has conducted ground-breaking research into knot theory. She still finds it hard to make friends or small talk.

More than 20 years ago, John Nunn became the youngest undergraduate at Oxford since Cardinal Wolsey. He took a first-class honours degree in maths at 18, followed by a doctorate at 20. At 23, he was a chess grandmaster. He now plays in international tournaments and writes chess books.

I and their university teachers Mary Lunn, senior maths fellow at St Hugh's College, Oxford, taught Ruth Lawrence, who was 12 when she arrived at the university.

"It's obviously different teaching someone of her age, but she would have been different had she been 18 because she was extremely good. She also produced an enormous amount of work and went to more lectures than most undergraduates I have had."

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Dr Lunn acted as Ruth Lawrence's personal tutor, but Ruth's father took full responsibility for his daughter's welfare, barely leaving her side. "You cannot expect a college to act in loco parentis because there is no capability for it to do so," Lunn says.

At interview, aged 10, Ruth was so impressive that Lunn felt she had no choice but to accept her. "She couldn't stand still for eight years. The most important thing was that she should be happy and enjoy what she was doing - and that's what happened. She never looked to me as if she was missing out socially."

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Irene Ault, tutor in pure mathematics at St Hilda's College, Oxford is teaching 13-year-old Sufiah Yusof, who started at the university last term.

As far as possible, the college authorities try to treat Sufiah like any other undergraduate, although they insisted that the girl's family be based in Oxford so that she could live at home.

Mathematically she is as mature as any student. "She doesn't have the distractions the others have," Dr Ault says. "I suspect she may well spend more time on her work."

Ault does not recommend going to university early. "If someone has got to this stage, it is difficult to know what else they might do and still develop mathematically."

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