# Exercise 10.3.3

Why don't we need to set or reset the prev attributes of objects in the implementation of the ALLOCATE-OBJECT and FREE-OBJECT procedures?

Because we're not using them. Having a singly linked free list is sufficient. We don't need the prev attribute and we don't even need the key attribute. Whenever we allocate and free objects, we're setting those fields anyway, so it does not matter that we don't reset them.