Hash Function

When we have m < |U|, we need some way of shoe-horning the universe into the table.

A hash function does this for us.

The hash value of an object is h(k).

A perfect hash function has the property that all the inserted objects K have a unique hash value.

For a perfect hash function h:

• Insert(k):
• Delete(k):
• Find(k): h(k)
• Member(k): ?

Acts just like the direct-address table: everything O(1) worst case.