 The following two-line program in pseudo-code illustrates Kripke’s claim. The symbol ‘\(\rightarrow\)’ is read ‘becomes’, and ‘=’ as usual means identity. The first instruction in the program is   \[r \rightarrow 2\]   This tells the computer to place the value 2 in storage location r (assumed to be initially empty). The second instruction   \[r \rightarrow r + 3\]   tells the computer to add 3 to the content of r and store the result in r (over-writing the previous content of r). The execution of this two-line program can be represented as a deduction: