4. (8 points) Jia, Yi, Bing, and Ding won the top 4 places in the school (no ties), and they said:
Jia: “I am neither first nor second”; Yi said: “I am neither second nor third”;
Bing: “My rank is adjacent to Yi's”; Ding: “My rank is adjacent to Bing's”.
Now it is known that Jia, Yi, Bing, and Ding respectively obtained the $A$, $B$, $C$, and $D$ places, and they are all honest students who do not lie. What is the four-digit number $\overrightarrow{\mathrm{ABCD}}=$ $\qquad$
【Solution】Solution: According to the analysis, Jia, Yi, Bing, and Ding respectively obtained the $A$, $B$, $C$, and $D$ positions, and they are all honest good students,

From Jia's statement, we know that Jia can only be third or fourth, so one of the last two positions must be Jia. From Yi's statement, we know that Yi can only be first or fourth. If Yi is fourth, then from Bing's statement, we know that Bing is third, which is a contradiction. Therefore, Yi can only be first, and Bing is second, Ding is third, and Jia is fourth. Hence, $A=4, B=1, C=2, D=3$, so the answer is: $\overrightarrow{\mathrm{ABCD}}=4123$.