Dear all;

I have a question.

In the attached file, there are two sheets embedded in 4-dim euclidean space R^4 (Note that they don't intersect). If we project them into 3-dim hyperspace, then the left part as well as the right part will be a line. I don't know what is the projected image of the middle part. I guess the image consists of two sheets one is behind the other, but if so how to join these two sheets with the lines. Please guide me

In fact, we can push one of the sheets so that we get two parallel sheets and so the projected image consists of a line. But I want the projected image in R^3 without doing this operation.

Thank you in advance