Podelski, Andreas Programming Logics, MPI for Informatics, Max Planck Society;
1-s2.0-S0304397596001971-main.pdf (Publisher version), 2MB
Podelski, A., & Smolka, G. (1997). Situated Simplification. Theoretical Computer Science, 173(1), 235-252. doi:10.1016/S0304-3975(96)00197-1.