Curvas algebraicas y la pregunta de Halphen
  This is an expository paper written in Spanish. This paper discusses the answer and ideas around the Halphen question: what are the pairs (g,d) that occur as the genus and degree of a smooth algebraic curve in projective 3-space.   Halphen's question has been studied by many authors, including Halphen in 1881, Castelnuovo in 1890, and was finally answered almost 100 years later by Gruson and Peskin in 1981. We (very briefly) sketch arguments by Castelnuovo in studying this question and comment on the ideas of the final answer provided by Gruson and Peskin. This paper is meant to be brief and elementary introduction to some ideas about algebraic curves embedded in projective space and as such, we start out with basic definitions such as that of an algebraic curve, genus and degree. Towards the end, we mention some modern developments about this question as well as directions of research. 
Cesar Lozano Huerta
math.HO math.AG