Short and sweet signing of Geneva accords ends tortuous negotiations. AFGHAN ACCORD

The signing of the Afghan peace accord here yesterday was short and simple, in sharp contrast to the long and complicated negotiations that led up to it. Under the agreement, the Soviet Union will begin pulling out its 115,000 troops from Afghanistan on May 15. One-half of the troops will be withdrawn by August 15, and all troops will be withdrawn within nine months.

The voluntary withdrawal amounts to an extraordinary concession of military defeat by the Soviets and could hold major implications for East-West relations (see accompanying article by Joseph C. Harsch). But there remain grave doubts that the war (already responsible for more than 1 million deaths and approximately 7 million refugees) will end. Resistance forces in Afghanistan have vowed to fight on until the communist regime in Kabul is toppled.

The second instrument signed only by the US and Soviet Union says the two superpowers ``undertake to invariably refrain from any form of interference an intervention'' in the internal affairs of Afghanistan and Pakistan. The superpowers also will respect commitments in the bilateral agreement between Afganistan and Pakistan, and ``urge all states to act likewise.''

In a letter to the UN Secretary-General before the signing the US made clear its support for the resistance. It said, in effect, it would restrain supplying the Afghan guerrillas as long as the Soviets practiced similar restraint in providing arms to the Kabul regime. First to enter the council chamber was UN Secretary-General Javier P'eres de Cu'ellar. He sat beside the blue-and-white UN flag at an octagonal table, open in the middle. Seated beside him, at his right hand, was UN Undersecretary-General Diego Cordovez.

Then came Afghan Foreign Minister Abdul Wakil and Minister of State for Foreign Affairs Zain Noorani for Pakistan. They sat to the right and left of Mr. P'eres de Cu'ellar, looking toward him - and avoiding looking at each other. It was the first time they had been together in the same room since the ``proximity discussions'' started in June, 1982.

They were followed by Soviet Foreign Minister Eduard Shevardnadze and Mr. Shultz, further round the table from Mr. Wakil and Mr. Noorani.

P'eres de Cu'ellar said the agreement represented ``a major stride in the effort to bring peace to Afghanistan and a sure reprieve for its people.''

He said it also constituted ``a testimony to the capacity of the United Nations to attain positive results on the most complex of issues when backed by the political will of its member states.''

He said the UN was prepared to assist the Afghans in meeting their needs.

The four instruments constituting parts of the Geneva agreement are:

Bilateral agreement between the Democratic Republic of Afghanistan and the Islamic Republic of Pakistan on principles of mutual relations, in particular of noninterference and nonintervention:

Declaration on international guarantees by the Soviet Union and the US:

Bilateral agreement between Afghanistan and Pakistan on voluntary return of refugees.

Agreement on the inter-relationships of the three instruments, with annexed memorandum of understanding on the UN role in monitoring application.