In mathematics, the HNN extension is a basic construction of combinatorial group theory.
Introduced in a 1949 paper Embedding Theorems for Groups by Graham Higman, B. H. Neumann and Hanna Neumann, it embeds a given group G into another group G', in such a way that two given isomorphic subgroups of G are conjugate (through a given isomorphism) in G' .
Read more about HNN Extension: Construction, Key Properties, Applications, Generalizations
Famous quotes containing the word extension:
“We know then the existence and nature of the finite, because we also are finite and have extension. We know the existence of the infinite and are ignorant of its nature, because it has extension like us, but not limits like us. But we know neither the existence nor the nature of God, because he has neither extension nor limits.”
—Blaise Pascal (1623–1662)