Based on prior knowledge, the Oldpeak feature is a numeric variable that measures ST depression. ST depression is an electrocardiographic finding associated with myocardial ischemia or heart disease. In general, a higher value of Oldpeak indicates a greater degree of ST depression and can be indicative of heart disease.

To create a dictionary of the relationship between the Oldpeak feature and the task of whether a patient shows a heart disease or not, we will examine typical values for each target class ('no' and 'yes') of the task.

Here is the requested dictionary:

```json
{
	"no": [0.0, 0.5, 1.0, 1.5, 2.0],
	"yes": [1.0, 2.0, 2.5, 3.0, 4.0]
}
```

The listed values are just examples, and actual ranges of values may vary depending on the specific dataset and domain knowledge. These values represent typical examples to showcase the relationship between the Oldpeak feature and the presence or absence of heart disease.