Symbols for Relational Algebra Expressions and Other Symbols…
Symbols for Relational Algebra Expressions and Other Symbols Symbols for relation schemas: R, S, T Symbols for relations: R, S, T, ∅ Symbols for Relational Algebra operators: ∪, -, π, σ, ρ, ⨯, ∩, Δ, ÷, ⨝, ⟗, ⟕, ⟖, ⋉, ⋊, ▷ Symbols for logical connectives: ∧, ∨, ¬ Symbols for comparison predicates: , =, ≤, ≥, ≠ Symbols for set-theoretical operations: ∈, ∉, ⊆, ⊂, ⊇, ⊃ Other mathematical symbols: ⊥, ⋅, ∃, ∀, ∘, ←, → All names (for example, for relations and attributes) should be written in normal font (no italics) to increase readability. All symbols should be surrounded by blanks to increase readability. Assume the following relation R: R X Y 1 ‘A’ 2 ‘B’ 3 ‘C’ Design a Relational Algebra expression that uses R to create a new relation S with the following contents: S X1 Y1 X2 Y2 1 ‘A’ 3 ‘C’ 2 ‘B’ 2 ‘B’ 3 ‘C’ 1 ‘A’
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