Density of the circular chromatic numbers of series-parallel graphs

Suppose G is a series-parallel graph. It was proved in [3] that either chi(c)(G) = 3 or chi(c)(G) less than or equal to 8/3. So none of the rationals in the interval (8/3, 3) is the circular chromatic number of a series-parallel graph. This paper proves that for every rational r epsilon [2, 8/3] boolean OR {3} there exists a series-parallel graph G with chi(c)(G) = r. (C) 2004 Wiley Periodicals, Inc.