To analyze the relationship between the feature 'IBS_POST' and the task (presence of chronic heart failure), we need to examine the distribution of 'IBS_POST' values for each target class.

Based on prior knowledge, the feature 'IBS_POST' represents the presence and type of angina pectoris in the patient before admission to the hospital. Angina pectoris is a characteristic symptom of coronary heart disease (CHD), which can lead to myocardial infarction and potentially chronic heart failure.

Let's analyze the relationship between 'IBS_POST' and chronic heart failure:

- For patients without chronic heart failure (target class = no), the possible values of 'IBS_POST' may include:
   - 'there was no СHD'
   - 'exertional angina pectoris'
   - 'unstable angina pectoris'

- For patients with chronic heart failure (target class = yes), the possible values of 'IBS_POST' may also include:
   - 'there was no СHD'
   - 'exertional angina pectoris'
   - 'unstable angina pectoris'

Based on the above analysis, the 'IBS_POST' feature does not provide a clear distinction between patients with and without chronic heart failure. The values of 'IBS_POST' are common in both target classes.

Here is the dictionary with the analysis results:

```json
{
	"no": ["there was no СHD", "exertional angina pectoris", "unstable angina pectoris"],
	"yes": ["there was no СHD", "exertional angina pectoris", "unstable angina pectoris"]
}
```

Please note that the values mentioned in the lists are just examples based on the categories provided in the feature description. The actual values may vary depending on the dataset.