Consider the log shown below.

lsn log
00 update: t1 writes p3
10 update: t1 writes p1
20 update: t1 writes p2
30 update: t2 writes p3
40 begin checkpoint
45 end checkpoint
50 update: t3 writes p4
60 t1 commit
70 update: t3 writes p2
80 t1 end
90 update: t2 writes p1
100 t2 commit crash, restart
in this log, we store information about 3 transactions. after the log record with lsn 100, the system crashes and then we restart. we use the aries recovery algorithm discussed in chapter 18 in the book. based on that, answer the following questions:

1. what is done during the analysis phase?
2. what is done during the redo phase?
3. what is done during the undo phase?
4. show the log when recovery is complete, including all non-null prevlsn and undonextlsn values in log records.

Whats are the different parts of no verbal comunication, especially body language?

Consider a slotted aloha system, where the time slot equals the fixed duration of each packet. assume that there are 4 stations a,b,c,d sharing the medium. (a) stations a,b,c,d receive one packet each from higher layers at times 1.3, 1.5, 2.6,5.7 respectively. show which transmissions take place when, according to the slottedaloha protocol; describe all transmissions until all four packets have been successful.when needed, each station has access to the following sequence of random number, provided by a random number generator and drawn uniformly between 0 and 1: (1) station a draws numbers: 0.31, 0.27, 0.78, 0.9, 0.9, 0.11, 0. (2) station b draws numbers: 0.45, 0.28, 0.11, 0.83, 0.37, 0.22, 0. (3)station c draws numbers: 0.1, 0.2, 0.3, 0.4, 0. (4) station d draws numbers: 0.36, 0.77, 0.9, 0.1, 0.1, 0.1, 0.1, 0. (b) in slotted aloha, a station transmits in each time slot with a given probability. what probabilities would you assign to each of the four stations so as to: (i) maximize the efficiency of the protocol? (ii) maximize fairness among the four stations? (c) will the efficiency increase or decrease if we modify slotted aloha as follows: (i) get rid of slots and allow stations to transmit immediately? (ii) implement carrier sensing? (iii) implement collision detection? (iv) implement collision avoidance?

What provides an array of buttons for quick access to commonly used commands and tools