The Pittsburgh Post-Gazette, in conjunction with PNC Financial Services Group, will hold a free town hall meeting on Tuesday to discuss the implications of the G-20 summit before the world leaders arrive in Pittsburgh.

The meeting, which will be held from 6:30 to 8 p.m. at the new August Wilson Center Theater on Liberty Avenue, Downtown, is the third in a series of town hall meetings that have previously touched on the economy and the presidency of Barack Obama.

The event is free, but attendees must register for a seat by calling 412-263-3850.

Post-Gazette Executive Editor David Shribman will moderate a panel of experts with strong worldwide experience and unusual global perspectives. They will provide an unvarnished look into the workings of an international summit such as the G-20.

"This summit will be a classic teaching moment for Pittsburgh and for much of southwestern Pennsylvania," said Dan Simpson, one of the panelists and a Post-Gazette associate editor.

A former U.S. ambassador to the Central African Republic, the Democratic Republic of Congo, and Somalia, where he served as ambassador and special envoy, Mr. Simpson retired from the U.S. Foreign Service after 35 years of assignments to countries in Africa, the Middle East and Europe.

World policy makers attending the G-20, he said, will be faced with tackling fundamental questions such as: "Are we at the end of the recession or do we still need to focus on the problems of the global financial system?"

Beyond that, he said, G-20 leaders are also most likely to grapple with such issues as climate change and the environment, and the global community's responsibility with regard to poverty and the developing world.

"Part of what we may discuss is the question: How does the G-20 forum develop and where does it fit in the international structure?" said James Dobbins, director of the RAND International Security and Defense Policy Center.

A former state department employee, where he worked for 35 years specializing in security issues and post-conflict resolution, Mr. Dobbins said that the challenge for G-20-type summits is often the ability to hammer out a consensus on long-debated agenda items.

Such summits, he said, "have long-settled agendas, but they are also driven by topical issues. In this case, he added, what may be an agenda aimed at discussing the global financial crisis will most likely also touch on sensitive topics like approving economic sanctions against Iran.

Also on the panel will be Susan Schwab, a former ambassador and U.S. trade representative from 2006 to 2009. Ms. Schwab is now professor of international trade and commerce, management and leadership, and U.S.-China relations at the University of Maryland School of Public Policy.

Barbara J. McDougall is a former foreign minister of Canada and chief finance minister of Canada. She served as a member of the Canadian Parliament for nine years, and is a holder of the Order of Canada, the nation's highest honor, given on behalf of Queen Elizabeth II.

Mrs. McDougall is currently an adviser at Aird & Berlis LLP, a law firm in Toronto, where she counsels clients on matters of international business development, corporate governance and government relations.