%0 Journal Article %T Toric ideals generated by circuits %A Jose Martinez-Bernal %A Rafael H. Villarreal %J Mathematics %D 2008 %I arXiv %X Let I be the toric ideal of a homogeneous normal configuration. We prove that I is generated by circuits if and only if each unbalanced circuit of I has a "connector" which is a linear combination of circuits with a square-free term. In particular if each circuit of I with non-square-free terms is balanced, then I is generated by circuits. As a consequence we prove that the toric ideal of a normal edge subring of a multigraph is generated by circuits with a square-free term. %U http://arxiv.org/abs/0812.0195v3