Based on prior knowledge, the relationship between the "maint" feature and the decision to buy the car can be analyzed as follows:

- If the maintenance cost is "very high", it is likely that the decision to buy the car would be rated as "unacceptable".
- If the maintenance cost is "high", the decision to buy the car could be rated as either "unacceptable" or "acceptable". Considering the fact that this is a categorical variable, it is difficult to determine whether "high" maintenance cost would more likely result in an "unacceptable" or "acceptable" decision.
- If the maintenance cost is "medium", the decision to buy the car could be rated as either "acceptable" or "good". Similarly, it is difficult to predict whether "medium" maintenance cost would result in an "acceptable" or "good" decision.
- If the maintenance cost is "low", it is probable that the decision to buy the car would be rated as either "good" or "very good".

Based on this analysis, the dictionary can be created as follows:

```json
{
	"unacceptable": ["very high", "high"],
	"acceptable": ["high", "medium"],
	"very good": ["low"],
	"good": ["medium", "low"]
}
```