I am trying to attack TAOCP once again, given the sheer literal heaviness of the volumes I have trouble committing to it seriously. In TAOCP 1 Knuth writes, page 8, basic concepts::Let $A$ be a finite set of letters. Let $A^*$ be the set of all strings in $A$ (the set of all ordered sequences $x_1$ $x_2$ ... $x_n$ where $n \ge 0$ and $x_j$ is in $A$ for $1 \le j \le n$). The idea is to encode the states of the computation so that they are represented by strings of $A^*$ . Now let $N$ be a non-negative integer and Q (the state) be the set of all $(\sigma, j)$, where $\sigma$ is in $A^*$ and j is an integer $0 \le j \le N$; let $I$ (the input) be the subset of Q with $j=0$ and let $\Omega$ (the output) be the subset with $j = N$. If $\theta$ and $\sigma$ are strings in $A^*$, we say that $\theta$ occurs in $\sigma$ if $\sigma$ has the form $\alpha \theta \omega$ for strings $\alpha$ and $\omega$. To complete our definition, let $f$ be a function of the following type, defined by the strings $\theta_j$, $\phi_j$ and the integers $a_j$, $b_j$ for $0 \le j \le N$:$f((\sigma, j)) = (\sigma, a_j)$ if $\theta_j$ does not occur in $\sigma$$f((\sigma, j)) = (\alpha \psi_j \omega, b_j)$ if $\alpha$ is the shortest possible string for which $\sigma = \alpha \theta_j \omega$$f((\sigma,N)) = (\sigma, N)$Not being a computer scientist, I have trouble grasping the whole passage. I kind of get the idea that is behind a system of opcodes, but I haven't progressed effectively in understanding. I think that the main problem is tat I don't know how to read it effectively. Would it be possible to explain the passage above so that I can understand it, and give me a strategy in order to get in the logic in interpreting these statements?
Please explain this formal definition of computation
formal languages;turing machines;computation models