Based on prior knowledge, arrhythmia in the anamnesis (feature nr_11) can be an important indicator of chronic heart failure. Arrhythmias are abnormal heart rhythms that can result from heart disease or other medical conditions, including chronic heart failure. Therefore, it is possible that the presence of arrhythmia in the patient's medical history (yes category) may indicate a higher likelihood of chronic heart failure.

To analyze the relationship between feature nr_11 and the task of identifying chronic heart failure, we need to examine the distribution of nr_11 values for each target class (yes or no).

Here is the dictionary with the details:

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

In this case, the feature nr_11 only has two categories - "no" and "yes". For the target class "no", the feature value can only be "no", indicating the absence of arrhythmia in the medical history. For the target class "yes", the feature value can only be "yes", indicating the presence of arrhythmia in the medical history.

Please note that in the dictionary, the feature values are represented as strings in lists, as required.