부산대학교 도서관

A polynomial map $f:k\sp n\to k\sp n$ over a field $k$ of characteristic not equal to 2, with components $f\sb i$ of total degree $\le 2$, is invertible if its Jacobian determinant is a nonzero constant. This result was originally proved by S. Wang , simplified by Oda, reformulated by D. L. Wright , and reported in the survey by H. Bass , E. Connell and Wright [Bull. Amer. Math. Soc. (N.S.) 7 (1982), no. 2, 287--330; MR0663785 (83k:14028)]. The heart of the proof (injectivity) is the same here as in the survey, which may be consulted for further references.