Gauss diagrams, unknotting numbers and trivializing numbers of spatial graphs

In this paper we introduce Gauss diagrams and four kinds of unknotting numbers of a spatial graph. R. Hanaki introduced the notion of pseudo diagrams and the trivializing numbers of knots, links and spatial graphs whose underlying graphs are planar. We generalize the trivializing numbers without the assumption that the underlying graphs are planar. Finally we discuss relations among the unknotting numbers and the trivializing numbers.