# Try Hard

Topics: SEPTA Regional Rail, Jaguar Racing, Number Pages: 2 (264 words) Published: April 6, 2011
Convention:

Subject: TPy – Answer Exercise x (y= 2 ie class on Monday and 4 ie class on Wednesday – x: serial number of exercise)

Attack file: TPyn_xxxxxx.doc (y= 2 ie class on Monday and 4 ie class on Wednesday – n: serial number of exercise, xxxxxx: student_code )

For example:
Subject: TP2 – Answer Exercise 1 (2: class on Monday)
file: TP21_123456.doc (2: Class on Monday – 1: Homework 1 – 123456 la Student ID)

Student code:
Student name:

Homework 1
17.22 Which of the following schedules is (conflict) serializable? For each serializable schedule, determine the equivalent serial schedules.

(a) r1 (X); r3 (X); w1(X); r2(X); w3(X)
(b) r1 (X); r3 (X); w3(X); w1(X); r2(X)
(c) r3 (X); r2 (X); w3(X); r1(X); w1(X)
(d) r3 (X); r2 (X); r1(X); w3(X); w1(X)

17.23 Consider the three transactions T1, T2, and T3, and the schedules S1 and S2 given below. Draw the serializibility (precedence) graphs for S1 and S2 and state whether each schedule is serializable or not. If a schedule is serializable, write down the equivalent serial schedule(s).

T1: r1(x); r1(z); w1(x)
T2: r2(z); r2(y); w2(z); w2(y)
T3: r3(x); r3(y); w3(y)

S1: r1(x); r2(z); r1(z); r3(x); r3(y); w1(x); w3(y); r2(y); w2(z); w2(y) S2: r1(x); r2(z); r3(x); r1(z); r2(y); r3(y); w1(x); w2(z); w3(y); w2(y)