Based on prior knowledge, the feature "Observing of arrhythmia in the anamnesis" (nr_11) can be related to the presence of chronic heart failure in patients. Arrhythmias are abnormal heart rhythms and can be a symptom or a consequence of heart failure. Therefore, it is possible that patients with a history of arrhythmia in their medical records (nr_11 = 'yes') have a higher likelihood of developing chronic heart failure.

To analyze the relationship between feature nr_11 and the presence of chronic heart failure, we can examine the distribution of nr_11 values within each target class.

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

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

Since the feature nr_11 is a categorical variable with two categories ('no' and 'yes'), we include both categories in the dictionary. Although the category 'no' is straightforward, we need to analyze the dataset to determine the presence of patients with chronic heart failure who also have a history of arrhythmia (nr_11 = 'yes'). If such cases exist, they will be included in the dictionary under the "yes" key.