Computability of 1-manifolds
  A semi-computable set S in a computable metric space need not be computable. However, in some cases, if S has certain topological properties, we can conclude that S is computable. It is known that if a semi-computable set S is a compact manifold with boundary, then the computability of \deltaS implies the computability of S. In this paper we examine the case when S is a 1-manifold with boundary, not necessarily compact. We show that a similar result holds in this case under assumption that S has finitely many components. 
Konrad Burnik (University of Zagreb), Zvonko Iljazovic (University of   Zagreb)
cs.LO math.LO