Universal Concepts

Here's a vocabulary:

• The universe of keys U is the set of possible key values we might want to include in our data structure (around 700k unique plate numbers).
• The number of slots m in the table T (same as |U| in this case).
• The objects in the universe $K \subseteq U$ are the things we actually insert into the table (the actual license-plate numbers in use).
• The number of objects is n=|K| (probably around 500k actual cars on the road, judging from a 1990 population of 1M people and an estimate of 0.49 vehicles per person ).
• The load factor $\alpha = n/m$ is the amount full the table is (0.73 in this case).