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Assignment 1

秦堤
2014013420

2.4 Yes, because we can identify tuples uniquely by the attribute name.

2.7 a. \(\Pi_{person\name}(\sigma{city=Miami}(employee))\)
b. \(\Pi_{person\name}(\sigma{salary>$100,000}(works))\)
c. \(\Pi_{person\name}(\sigma{salary>$100,000}(works))\cap\Pi_{person\name}(\sigma{city=Miami}(employee))\)