August 26, 1986

College costs have increased sharply in the last few years, but remain relatively stable in proportion to the income of most families with children in college, according to a new study. The exception, it said, are ''selective private colleges and universities where price increases are quite pronounced.'' Those schools have ''little need to exercise restraint,'' the study said, because applicants continue to outnumber the available places for them, despite price increases. The study, conducted by the American Enterprise Institute for Public Policy Research and issued last week, found that despite popular perceptions, ''for most median-income families with a child enrolled in college, higher education does not require a significantly greater share of family income than it did 10 years ago.''

CENTURIES of wisdom about chess endgames - the established truths about who will win or draw when the game comes down to its last pieces - have suddenly been overthrown by a few weeks of work by computers. An innovative technique, sharply different from the programs used by computers that play chess from beginning to end, has been put to the task of completely solving all of the possible endgame positions with five or fewer pieces. It has discovered that many basic positions, long thought to be draws with best play by both sides, actually can be won by one side. The results have not until now been published, but one grandmaster, Arthur Bisguier, a former United States champion on the staff of the United States Chess Federation, has examined them, to his astonishment and chagrin. ''By dint of brute force, the program has unearthed all kinds of results which eluded us,'' Mr. Bisguier said. ''It was mindboggling for me. When this becomes public, it will give a considerable edge to those people in possession of the analysis.''

The Wells Fargo Bank yesterday cut its prime lending rate to 7.5 percent, from 8 percent, becoming the first large bank to do so since the Federal Reserve cut its discount rate last week. Wells made its move too late in the day for banks in Chicago and New York to respond. But they will probably cut their prime rate starting today to remain competitive, economists said.

Just a year after the Taft Broadcasting Company moved to become a major force in broadcasting, it is considering the sale of five of its independent television stations, the company said yesterday. Last year Taft bought five television stations from the Gulf Broadcasting Company for $760 million. Taft already owned seven stations. Now it is planning to sell three of those and two from the Gulf deal.

Not long ago, Horace Greeley 4th was going west, on Route 46, when the phone rang. John Braun, a purchasing agent, was calling, and he wanted to buy 200,000 pounds of cocoa from Mr. Greeley, who does much of his food brokerage business by car phone. Like any hard-charging executive of the 80's, Mr. Greeley, 50 years old, enjoys doing the maximum number of things at once. On this morning, he was driving to biscuit research at Nabisco's headquarters here to drop off cocoa powder for a secret project, and he was working the car phone.