To analyze the relationship between the feature ANT_CA_S_n and the task of determining whether the patient shows chronic heart failure, we can look at the distribution of ANT_CA_S_n values for the different target classes.

Here is the dictionary representing the relationship between the feature and the task:

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

Based on this analysis, the ANT_CA_S_n value of "yes" is associated with the target class "no" (indicating no chronic heart failure), while the ANT_CA_S_n value of "no" is associated with the target class "yes" (indicating chronic heart failure).

Please note that the dictionary only includes the values that have a clear association with the target class.