Impossible combinations are combinations of levels on the attributes to be excluded at the trade-offs page to avoid confusion. Specifying impossible combinations removes those combinations from the trade-offs and spares you from having to think about unrealistic questions. However, you should only specify these combinations if they will cause confusion.
Adding impossible combinations
![Adding impossible combinations](https://data.1000minds.com/youtube/youtubehero/c4dcf547-5b1f-405a-94e3-e0a1414155b0.jpg)