Figure 3.3a: Initial Memo After Copy In of Query 3.2

           Figure 3.3b shows the fully expanded memo structure (of logical expressions only) for query 3.2.¹⁰ It represents the memo resulting from the application of associative and commutative join transformation rules to memo 3.3a.

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10. By figure 3.2 we mean either figure 3.2a or figure 3.2b, both of which represent query 3.2. The query trees in 3.2a and 3.2b are logically equivalent -- they represent the same logical query.

3. Fundamental Concepts:	<Models> <Log> <Query Trees> <Groups> <Memo> <Phys> <Item> <Rules> <Opt Stages> <Find Best> <Complexity>   3.1: EQJOIN     3.2a: Query Tree     3.2b: Equiv.     3.3a: Init Memo     3.3b: Memo     3.3c: Key     3.4: Complexity     3.5: Phys Memo     3.6: Plan     3.7: Pred.     3.8: Op Types     3.9: Rule

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