A 31 year old associate professor from the University of California at Berkeley, who is credited will a series of significant strides in some of the least explored regions of mathematics and physics, will join the Mathematics Department as a tenured professor next fall.

Chilford Taubes, who did his graduate work a Harvard from 1976 to 1980 is widely recognized for his work on non-linear differential equations and their applications to geometry and topology--the study of surfaces. Scientists say that such work is likely to play a key role in certain aspects of theoretical physics.

The appointment of Taubes is the second successful tenure appointment in the Math Department this year. Last month department members confirmed the appointment of Benedict H Gross, a number theorist from Brown University.

Taubes is the first mathematical analyst the University has appointed in recent years, said Graustein Professor of Mathematics Raoul Bott. "No one here has his level of expertise in that area," he added.

The appointments of Gross and Taubes will help compensate for a number of Math Department losses to both retirement and other universities during the last two years.

Although a Swiss mathematical physicist turned down a rare joint tenure position with the Physics Department earlier this year, professors said that the appointment of Taubes is unrelated to their ongoing attempt to lure a combined specialist.

In the fall Jurg Froelich, who teaches in Switzerland, turned down the joint math-physics tenure offer, citing a desire to remain in his homeland.

Taubes, however, said this week he rejected offers from other universities to come to Harvard to assume the lifetime teaching post.

"[Harvard] is an exciting place to do math and science in general. The University is very responsive to research and the students there are very interested in the latest work," he said.

Taubes' most significant contribution has been "understand differential equations that have been important in topology," said Professor of Mathematical Physics Arthur M. Jaffe, who taught Taubes and then co-authored a book with him "It turns out that these equations have important con- senuences for geometry.

More specifically, topology is the study of properties of geometric figures which do not vary when the figure is transformed in various ways.

While his work is likely to figure prominently in theoretical high energy physics, Taubes said that currently technology is not advanced enough to use or test his results experimentally