February 26, 1985

''But sir,'' said the student during a seminar on ethnicity that was unusually lively for a Monday morning class, ''it looks like ethnic lines have eroded in New York. Jews, for example, are more assimilated than ever.'' The professor seemed pleased to be challenged but stuck to the thesis of his lecture. ''The city is more heterogeneous now than ever,'' he said.

The National Science Foundation said today that it would spend $200 million to create supercomputer centers at four of the nation's leading universities. The move is the broadest Federal effort yet to promote research using advanced computer technology. Federal officials said the primary motive for the five-year program was a ''desperate, overwhelming need'' among academics for access to supercomputers that could help solve a wide range of basic research problems. Some also said it constituted an American version of Japan's Super- Speed Project, a joint effort of government and industry to build the next generation of high-speed computers.

The Defense Department's top arms control official said today that it was ''a great mistake'' for the United States to continue honoring past accords with the Soviet Union while Moscow was violating ''quite important provisions'' of those agreements. Testifying before the Senate Foreign Relations Committee, the official, Richard N. Perle, Assistant Secretary of Defense for International Security Policy, said it was time to end the ''double standard'' of having Washington adhere ''to every crossed 't' and dotted 'i' '' while letting the Russians ''think they could play fast and loose with these accords.'' The Soviet Union has denied that it has violated arms accords and has in turn accused the United States of breaking the agreements. Query on 1979 Agreement Mr. Perle made the comments when he was asked by Senator Christopher J. Dodd, Democrat of Connecticut, whether he believed President Reagan should continue to abide by the 1979 strategic arms accord with the Soviet Union, which was never ratified, or should dismantle some older Polaris submarines when the seventh Trident submarine, the Alaska, starts sea trials at the end of the year.

Representative Dan Rostenkowski, the chairman of the House Ways and Means Committee, said last night that the time was ripe politically this year for a complete restructuring of the Federal income tax system, and he urged business leaders not to stand in the way of such legislation. ''We only get a chance at profound reform every decade or so,'' Mr. Rostenkowski said in a speech to the Economic Club of New York at the New York Hilton. President Reagan and his Treasury Secretary, James A. Baker 3d, are behind the idea, Mr. Rostenkowski said, and ''Congressional leaders, while rarely enthusiastic about projects which demand such painful choices, appear ready for, or resigned to, the long march.'' Moreover, he added, ''taxpayers are slowly, but surely, warming up to the rewards of reform, and woe to the politician that disappoints the taxpayer.''

The dollar surged to record highs yesterday, encouraged by Washington's apparent reluctance to intervene in foreign-exchange markets to force the dollar down. Currency traders at their computer screens expressed astonishment as light, nervous trading propelled the dollar to levels never before seen. Many said they had no relevant experience to judge what might happen next. ''We're in uncharted waters, and it's anybody's guess where the dollar is going to stop,'' said Lawrence L. Kreicher, an economist at the Irving Trust Company.