I would like to start a discussion about the most basic principles behind quantum eraser experiments. I understand this has been debated here many, many times and for some of you there is nothing to talk about, but I still find it interesting and would like to get some of your opinions. I know there are many different experiments of this type that have been proposed and also realized. Some of them try to show some new aspect of it and become quite complex, but I would like to focus on the most simple ones. It seems like the basic concept is that if we have two particles which are entangled with respect to some observable, an action on one of them that deletes information will have some non-local implication on the other particle. I understand that depending on your favorite interpretation you may deny non-locality, but at least that's what at first sight it looks like. If you have the two particles with some 2-state observable maximally entangled, which means this is a singlet and you take some action on the particle on the right that will make it impossible to distinguish between these tow states, then in principle it should be possible to observe interference (after sending a few particles of course) on the other side right?. Well, I know you will say "No", this only happens if coincidence counting is done. I wonder how we can model this concept if we send the singlets one at a time, don't loose any, and don't have any noise or non-entangled particles. In real-life we would have to choose a particular type of particle such as a pair of photons produced by down-conversion, some kind of fermion or even atoms, and choose the particular observable that we are entangling. But maybe we can think of a generalized example without getting into the details. My understanding is that in principle what we have is complementarity between "path" distinguishability and interference. But I think you might have different concepts and opinions. If you would prefer to talk about a particular simple model, I am willing to discuss that.