February 11, 1986

The leader of Haiti's four-day-old interim Government said today that the new ruling body was committed to the development of a ''real and functional democracy.'' In a brief address at the formal installation of a 16-member Cabinet that is to help administer this country of six million people, the leader, Lieut. Gen. Henri Namphy, promised free elections. He said that Haiti's democracy would be ''founded on absolute respect for human rights, press freedom, the existence of free labor unions and the functioning of structured political parties.'' General Namphy, speaking in French at the huge presidential palace in downtown Port-au-Prince, did not say when elections would be held. But he said the interim Government was ''eager to hand over power to a democratically elected government.''

In a cataclysmic drama played out once every 76 years, Halley's comet has swept to within 55 million miles of the surface of the Sun and once again has been hurled back toward exile in the farthest reaches of the solar system, renewing a cycle as old as history. Even now, as it begins another 7 billion-mile trip out beyond Neptune and back, the famous comet's ice is flashing into hot gas, its dust is being blasted away and pockets of trapped gas are exploding into enormous, spectacular tails. The comet is at its biggest, its brightest and its best. Unfortunately, this historic period of perihelion, one of the greatest shows in the solar system, is happening on the opposite side of the Sun from Earth. The comet will not be visible to Earthbound viewers again until next month.

The A.&P. supermarket chain removed all containers of Tylenol capsules from its shelves late yesterday after a woman in Yonkers died of poisoning from cyanide believed to have come from an Extra-Strength Tylenol capsule. The Yonkers police said last night that a 23-year-old Peekskill woman died Saturday after taking the nonprescription pain reliever. The woman, Diane Elsroth, who was visiting a friend in Yonkers, had bought the drug at an A.&P. store in Bronxville. In reaction to the incident, the Federal Food and Drug Administration warned Yonkers-area residents to avoid using all Tylenol capsules and warned consumers not to use Tylenol from 200,000 bottles with the lot number ADF 916 and an expiration date of May 1987. The New York City Health Department last night also advised consumers to avoid all Tylenol capsules.

People Express Inc., in a bold attempt to expand its low-cost system to the recently acquired Frontier Airlines and open the West to more East Coast travelers, said yesterday that it had cut the one-way fare between Newark and Denver from $99 to $69. It also cut fares to more than 100 other cities served by its new subsidiary. In a move to lower Frontier's costs to compensate for the reduced fares. Stephen Schlachter, a People executive, said at a news conference that his company would try to apply its management approach to Frontier's 4,000 mostly unionized workers. People's employees, who are not unionized, perform a variety of jobs other than their specialties and are considered part of the company's management. They are also required to own stock in the company.

The recording industry, while enjoying the booming market for compact disks, is also having to grapple with the new product's inevitable growing pains. Mindful of the boom-and-bust cycles of other technologies - notably video games and, to a lesser extent, personal computers - the industry's leaders in the United States, CBS Records and Warner Records, are proceeding cautiously in trying to solve production and distribution problems, analysts say. In particular, the analysts add, the companies have been wary about deciding whether to invest heavily in manufacturing plants of their own. Meanwhile, the 12 plants that exist worldwide, including just one in this country, are struggling to keep up with demand for the plastic disks, whose sound quality is generally held to be superior to records and cassettes. Gaining Market Share ''Consumers are tearing the disks off the shelves,'' said Barry Bergman, owner of the Record Bar, a leading retail chain based in Durham, N.C., that is having trouble maintaining supplies.