The gpsemantics readme file seems to be errant. 

 * Implements Goldberg and O'Reilly's semantic Order and Majority
 * problems. See the README.

I presume this file has information about what the problem is doing and which 
papers it references. Possibly these are the papers?

[24] D. E. Goldberg and U.-M. O’Reilly, “Where Does the Good Stuff
Go, and Why?,” in EuroGP 1998, W. Banzhaf, et al., Eds. Berlin:
Springer-Verlag, 1998, pp. 16–36.

[25] U.-M. O’Reilly and D. E. Goldberg, “How Fitness Structure Affects
Subsolution Acquisition in Genetic Programming,” in GP ’98, J. R.
Koza, et al., Eds. S

-- ray