Based on prior knowledge, we can analyze the relationship between the feature "n_p_ecg_p_12" and the task of determining whether the patient has chronic heart failure.

We can assume that if the patient has complete right bundle branch block (RBBB) on the electrocardiogram (ECG) at the time of admission to the hospital (n_p_ecg_p_12 = "yes"), it might be an indication of the myocardial infarction complications leading to chronic heart failure. On the other hand, if the patient does not have complete RBBB (n_p_ecg_p_12 = "no"), it suggests that chronic heart failure may not be present.

Based on this analysis, we can create the following dictionary:

```json
{
	"no": ["no"],
	"yes": ["yes"]
}
```

Note that in this case, the only possible value for the feature "n_p_ecg_p_12" for the target class "no" is "no," and the only possible value for the feature "n_p_ecg_p_12" for the target class "yes" is "yes."