More on SOP1 and SOP2

This paper continues the work in [S. Shelah, Towards classifying unstable theories, Annals of Pure and Applied Logic 80 (1996) 229–255] and [M. Džamonja, S. Shelah, On ◃∗-maximality, Annals of Pure and Applied Logic 125 (2004) 119–158]. We present a rank function for NSOP1 theories and give an example of a theory which is NSOP1 but not simple. We also investigate the connection between maximality in the ordering ◃∗ among complete first order theories and the (N)SOP2 property. We prove that ◃∗-maximality implies SOP2 and obtain certain results in the other direction. The paper provides a step toward the classification of unstable theories without the strict order property.