System R



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.1 tid' .

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.2 tid' .

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. 3. .

----------------------------------------------- 1 +-------+ 2 +-------+---------+ 3 +----+-----------------------+ 4 +-------------+ 5 +-------------+ ( tc) ( tf)

.4 .

. . . -------+--------+----- --------- COMPILESECT , , - , L---------------------- L--------- ------ --------- INTERSECT , - - 覦 ..