More on removing item from cart

I posted a question about this a couple days ago. Many thanks to Dan and Erik for your suggestions, which I've thoroughly investigated. Unfortunately, I still have not got the problem resolved, and I've been working on it for so long that I think my brain may be permanently scrambled. I do, however, have a strong suspicion about where one part of the problem may lie, and would appreciate some clarification on this issue. I have a shopping cart array $cart, with $artID as its key ($artID is an integer). $cart is set as a session variable. The cart prints to the browser with checkboxes next to each article and instructions to uncheck the checkbox and click on the "Save Changes" button to remove items from the cart. (This is the part that doesn't work.) The checkbox input has "NAME = checkbox[$artID] VALUE = yes", and there is a hidden input with "NAME = save VALUE = true" that are passed when the form is submitted. My suspicion is that my problems are caused by the fact that I'm trying to relate two arrays - $cart and $checkbox. They do have the same key ($artID), but I haven't been able to find any way to get them to work together. All I want this piece of code to do is return a $cart that doesn't include any articles ($artID) that weren't checked. I've tried dozens of variations, but now I think most of them have been reading from one or the other array and therefore failed. If anybody has any suggestions on this I'd be very grateful. I've been working on this for days (I'm very new to PHP), and it just doesn't seem like it should be that difficult. Thanks, Vicki