Poland's communist authorities and the independent Solidarity trade union federation opened talks today that could pave the way to a form of power-sharing in this ostensibly one-party state.

The talks focussed on procedural issues in preparation for what are likely to be the most detailed and lengthy negotiations between Solidarity and the government in more than seven months. Both sides have stressed that the stakes are high, with success meaning the creation of a national consensus and failure the danger of all-out confrontation.

After three hours of talks, partial agreement was reported on an agenda. The two sides agreed to set up a working group to discuss how to stabilize the economy over the winter.

Other topics scheduled were Solidarity's demands for greater access to the mass media, price reform, and law and order. But disagreement persisted over the form of negotiations on the union's call for an independent body to supervise the economy and for new electoral regulations.

In opening the session today, the chief government delegate, Trade Union Minister Stanislaw Ciosek, invited Solidarity to take part in a new council for national conciliation. He noted recent serious political tension and strikes that were still continuing in some parts of the country.

"This is a time of unrest, but also a time of hope," he said. Earlier, Solidarity's chief press spokesman, Marek Brunne, said the union did not intend "an all-out bayonet charge at the talks."

Solidarity was represented by its vice chairman, Stanislaw Wadalowski.

The negotiations stem directly from the unprecedented meeting Nov. 4 of the leaders of Poland's three most powerful institutions: the Communist Party, Solidarity and the Roman Catholic Church. The party leader, Gen. Wojciech Jaruzelski, has made clear he is ready to make substantial concessions to Solidarity in return for its support and an end to strikes.

The exact nature of the power-sharing arrangement likely to emerge is unclear. It will depend on bargaining which could include a trade-off between Solidarity's demands for greater access to the mass media and radical economic reform and the party's need to broaden its political base and get the country back to work.

Meanwhile, despite strike settlements at major factories, there was still scattered labor unrest. In Siedlce, delegations arrived from all over Poland to support farmers who have occupied local party offices in protest of the government's agricultural policies.

Up to a quarter of a million students were preparing to strike for the removal of the rector of the university in Radom, south of here. In 11 of Poland's 49 provinces, a dispute over deliverers' commissions halted newspaper deliveries.

And, in a novel protest, 11 prisoners in Rzeszow climbed up a 140-foot chimney to demand penal code reform and the review of sentences.