On the Variety of Rational Curves of Degree $d$ in $\Bbb P^n$
  We construct the canonical structure of an irreducible projective variety on the set of connected curves of degree $d$ in $\Bbb P^n$ with rational components (some components can be multiple). The set of rational curves is open subset in the Zariski topology under this structure. 
Pavel Katsylo (Independent University of Moscow)