Typically, modeling starts with an informal session in which you collect the basic definitions and the most simple relationships in the model.

一般来说，建模从一次非正式的会话开始，期间可以收集到模型中基本的定义和最简单的关系。

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The New York meeting co-chaired by President Obama, British Prime Minister Gordon Brown and Pakistani President Asif Ali Zardari was the first summit-level session of the informal Friends of Democratic Pakistan grouping, and it brought together leaders of some 25 countries and organizations.

VOA: standard.2009.09.24

Simon Coveney, Ireland's agriculture minister, called for the informal session in Brussels, Belgium, inviting the EU Health Commissioner Tonio Borg and ministers from other European Union nations.

CNN: EU officials to meet about horse meat scandal

Ministers and officials will be coming to Brussels fresh from an informal two-day session at UN climate convention headquarters in Bonn, where they've heard United Nations Environment Programme chief scientist Joseph Alcamo outline a few key issues.

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The manual includes session plans, teaching materials, assistance in teaching techniques and other resources to run informal training in media and journalism.

UNESCO: Communication and Information