“…The first set of 6 instances named SY1-SY6 are taken from Stoyan and Yaskov (1998), and the second set of 12 instances identified as SY12, SY13, SY14, SY23, SY24, SY34, SY56, SY123, SY124, SY134, SY234, SY1234 are taken from Akeb and Hifi (2008). Note that the second set of instances are obtained by concatenating the six original instances of the first set, e.g., SY12 is obtained by concatenating SY1 and SY2, and SY1234 is obtained by concatenating SY1, SY2, SY3, SY4, etc.…”