Consider the relation r(a, b,c, d) with fds ab -> c, c-> d, d-> a. what is the 3nf status of r? 1. ris in 3nf. 2. ris not in 3nf. it must be deconstructed into r1(a, b,c) with ab-> c and r2(a, b,d) with d-> a. s. r is not in 3nf. it must be deconstructed into r1(a, b,c) with ab-> c, r2(a, b,d) with d-> a and r3(a, b,d) 4. ris not in 3nf but there is no unique deconstruction.

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?

Aisha has finished working on a word processing document that contains 15 pages. she has added some special elements in the first three pages, page 9 and 10, and page 15 from the document. she wants to print only these pages to see how they look. which option is the correct way to represent (in the print dialog box) the pages that aisha wants to print

The blank button automatically displays next to the data when you select a range of numeric data which is an available option for creating a chart