Corrigendum for "A Systematic Approach to Programming" (26.04.2020) - the binary decision tree for the operation INCH described on p. 22 in the second last paragraph ("The edge from INCH to FINDS is taken iff...") is incorrect. It is true that FINDS is the next operation if h is smaller than the cardinality of the current block. But if this is not the case then one does not necessarily continue with $\cong$ (isomorphic symbol). Instead one has to check whether there is a block larger than k. If this holds then one has to continue with the operation NB, otherwise with $\cong$. This implies an additional edge in the CFG from INCH to NB in Figure 8. Thanks to Tien Hung Ngo for pointing this out.