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

After conducting a thorough analysis of the relationship between the feature "FIB_G_POST" and the task of determining if the patient shows chronic heart failure, it is found that the feature has two categories: "no" and "yes". 

In this case, it can be determined that if the value of "FIB_G_POST" is "no", it indicates that the patient does not show chronic heart failure, while if the value is "yes", it indicates that the patient does show chronic heart failure.

As a result, the dictionary provides the possible values of feature "FIB_G_POST" for each target class, "no" and "yes".
```