4. Let $T$ be a set of ordered triples $(x, y, z)$, where $x, y, z$ are integers, and $0 \leqslant x, y, z \leqslant 9$. Two players, A and B, play the following game: A selects a triple $(x, y, z)$ from $T$, and B has to guess A's chosen triple using several "moves". One "move" consists of: B giving A a triple $(a, b, c)$ from $T$, and A responding with the number $|x+y-a-b|+|y+z-b-c|+|z+x-c-a|$. Find the minimum number of "moves" required for B to determine A's chosen triple.
(Bulgaria provided)
Solution: Two "movements" are not enough. Because each answer is an even number between 0 and 54, i.e., there are 28 possible values for each answer. The maximum number of possible results from two "movements" is $28^{2}$, which is less than the 1000 possible values for $(x, y, z)$.

Below, we prove that 3 "movements" are sufficient to determine the triplet chosen by A.

In the first "movement," B gives A the triplet $(0,0,0)$, and A's response is $2(x+y+z)$, so B can determine the value of $s=x+y+z$. Clearly, $0 \leqslant s \leqslant 27$. Without loss of generality, assume $s \leqslant 13$. In fact, if $s \geqslant 14$, then the $(a, b, c)$ given by B to A in the following process can be changed to $(9-a, 9-b, 9-c)$, and the triplet $(x, y, z)$ can still be determined.

If $s \leqslant 9$, in the second "movement," B gives A $(9,0,0)$, and A's response is $(9-x-y)+y+z+(9-x-z)=18-2x$, thus the value of $x$ can be determined. Similarly, in the third "movement," B gives A $(0,9,0)$, and the value of $y$ can be determined. Therefore, $z=s-x-y$ can be determined.

If $9 < s \leqslant 13$, in the second "movement," B gives A $(0, s, 0)$, and A's response is $|s-x-y|+|s-y-z|+|s-x-z|=3s-2(x+y+z)=3s-2s=s$, thus the value of $s$ can be determined. In the third "movement," B gives A $(9, s-9, 0)$, and A's response is
$$
\begin{array}{l}
|s-9-x-y|+|s-9-y-z|+|9-x-z| \\
=(9-x)+(s-9-y)+(9-x-z) \\
=18-2(x+z) .
\end{array}
$$

Thus, the value of $x+z$ can be determined. Similarly, the values of $x$ and $z$ can be determined. Therefore, the value of $y$ can be determined.
In summary, the minimum number of "movements" required is 3.