A Decomposition Theorem Concerning Linear Graphs H. Trent Indiana University Mathematics Journal 1964 text pdf 10.1512/iumj.1964.13.13020 10.1512/iumj.1964.13.13020 en Indiana Univ. Math. J. 13 (1964) 325 - 328 state-of-the-art mathematics http://iumj.org/access/