Incompressible surfaces in handlebodies

Let F be a compact surface and let I be the unit interval. This paper gives a standard form for all 2-sided incompressible surfaces in the 3-manifold F x I. It also supplies a simple sufficient condition for when 2-sided surf aces in this form are incompressible. Since F x I is a handlebody when F ha s boundary, the paper applies to incompressible surfaces in handlebodies. ( C) 2000 Elsevier Science Ltd. All rights reserved.