On the 2-parallel chromatic index of Steiner triple systems

The 2-parallel chromatic index ″ (8) is the minimum number of colours required to colour the blocks of a Steiner triple system 8 so that any two parallel blocks receive different colours. The value of ″(v) = min {″ (S): S is an STS(v)} is determined for all admissible v. It is further shown how the 2-parallel chromatic index is related to the independence number and a complete analysis for all STS(v), v ≤ 15 is given.