Irene Heim

Irene Roswitha Heim is a linguist and noted specialist in semantics. She was a professor at the University of Texas at Austin and UCLA before finally moving to the Massachusetts Institute of Technology in 1989, where she is Professor of Linguistics and a former Head of the Linguistics Section of the Department of Linguistics and Philosophy.
Research.
Her 1982 University of Massachusetts Amherst dissertation "The semantics of definite and indefinite noun phrases" is considered a classic text and a major milestone in formal semantics. In the second chapter of the work she argued (developing an insight by the philosopher David Lewis) that indefinite noun phrases like "a cat" in the sentence "If a cat is not in Athens, she is in Rhodes" are not quantifiers but free variables bound by an existential operator inserted in the sentence by a semantic operation that she dubbed existential closure. In the third chapter of the work she developed a compositional dynamic theory of (in)definites. This work, along with Hans Kamp's roughly contemporaneous 'A Theory of Truth and Semantic Representation' (1981), became the founding work in the influential tradition of dynamic semantics. 
She is also the co-author with Angelika Kratzer of an influential textbooks of formal semantics, and is a co-editor (also with Kratzer) of the journal "Natural Language Semantics".
In 2010 Irene Heim was awarded a Senior Fellowship of the Zukunftskolleg at the University of Konstanz.