  Let G be a finite graph on [n] = {1,2,3,...,n}, X a 2 times n matrix of
indeterminates over a field K, and S = K[X] a polynomial ring over K. In this
paper, we study about ideals I_G of S generated by 2-minors [i,j] of X which
correspond to edges {i,j} of G. In particular, we construct a Groebner basis of
I_G as a set of paths of G and compute a primary decomposition.
