I am trying to describe a region of a random walk on a graph (don't worry if you don't know what it is, visualise it as a physical space, e.g. a park). This graph has a part that if you go there, you cannot leave. I named this part "trapping".
I am trying to find a word for the other part, the one you can freely roam around but once you leave, you cannot come back. I thought of repelling, but repelling implies an action, that the part tries to get rid of you. I cannot find anything that fits here. Do you have any suggestions?
I'm also happy to change trapping to something else of it makes it easier to find an antonym.
Edit: This is for a paper I'm writing that has to do with random walks on a graph. I didn't want to scare people off with mathematical lingo, so I talked about physical space.