Completeness by Forcing

The completeness of the infinitary language ℒω1,ω was proved by Carol Karp in 1964.We express and prove the completeness of infinitary first-order logics in the institution-independent setting by using forcing, a powerful method for constructing models. As a consequence of this abstraction, the completeness theorem becomes available for the infinitary versions of many ‘first order’ logical systems that appear in the area of logic or computer science.