It turns out that the whole notion of a 'reference count' that tracks the exact number of handles is unnecessarily powerful. If you weaken the guarantee to two

It turns out that the whole notion of a 'reference count' that tracks the exact number of handles is unnecessarily powerful. If you weaken the guarantee to two states - 0 or greater than 0, you can do even better. See SNZI (scalable non-zero indicators): http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.83.3091&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.83....