Focus: It is depending on the shape and structure of A: tall, square, symmetric. For each technique, give the relevant matrix equations to obtain the solution x, and point out the properties of the matrices involved. You can allude to tuple numbers in your clarification.This is an example only. StudentMarksTest1[1:30] StudentMarksTest2[1:30] StudentMarksTest3[1:30] (1 mark) StudentTotalScore[1:30] (10 mark) [12] (b.a) (i.i) - outside loop zeroing total for loop (sum in example below) - loop for all students - input name and all test scores - in loop adding a student's total - storing the total - inside loop printing student's name and total - outside loop calculating class average - printing class average sample algorithm: [7] (ii.i) any relevant comment with regards to efficient code (e.g. single loop) [1] (c.a) Many correct answers, these are examples only. 1 mark per data set and reason Set 3: 30, 35, 35 Reason: valid data to check that data on the upper bound of each range check is accepted Set 2: 31, 36, 36 Reason: invalid data to check that data above the upper bound of each range check is rejected [2] 3 UCLES 2010 0367/02/SM/20 [Turn over (d) (i) Maximum 5 marks in total for question part Maximum 3 marks for algorithm Description (max 3) - set variable called HighestScore to zero and variable called BestName to dummy value. For each error identified + suggested correction line 5: this should read IF x > h THEN h = x line 17: PRINT h should come after the end of the repeat loop line 8: this should read UNTIL c = 20 or UNTIL c >= 20 or UNTIL c > 19 [3] 5 UCLES 20367/02/SM/20 [Turn over 5 (a) 5 [1] (b) Field: At Risk Age in Years Type Map Position Table: TREES TREES TREES TREES Sort: Show: 9 9 Criteria: True >100 or: One mark per correct column. [4] 6 (a) marking points: the way to find and print the largest value a 1 mark the way to find and print the largest value b 1 mark the way to find and print the largest value c 1 mark sample algorithm: INPUT a, b, c IF a > b AND a > c THEN PRINT a (1 mark) ELSE IF b > c THEN PRINT b (1 mark) ELSE PRINT c (1 mark) [3] (b) marking points: loop construct 2221 mark check if number is an integer 1 mark counting the number of integers input 1 mark output count value (outside the loop) 1 mark sample algorithm: FOR x 1 TO 10200 (1 mark) INPUT Number Difference INT(number) - Number (11 mark) IF Difference = 10 THEN Total Total + 11 (1 mark) NEXT x PRINT total (1 mark) (NOTE: alternative to lines 1 and 14: IF INT(Number) = Number THEN Total Total + 1 (2 marks) ) [4] (c) Description of any two sets of test data. Many correct answers, these are examples only. 1000 whole numbers to ensure that loop works properly 900 whole numbers and 100 numbers with decimal places to ensure that the routine distinguishes correctly [2] 6 UCLES 2019 0478/02/SM/20 7 (a) 7 [1] (b) Hg, Cs [2] (c) Element symbol [2 marks] (ii) Clearly explain, with a picture if helpful, how the data structure will evolve for arbitrary n, and derive the worst-case time complexity for the whole operation of inserting the n + 1 keys. [2 marks] (b) Repeat (a)(i) and (a)(ii) for a 2-3-4 tree, with some scratch work showing the crucial intermediate stages. [2+2 marks] (c) . . . and for a B-tree with t = 3, again showing the crucial intermediate stages. [2+2 marks] (d) . . . and for a hash table of size 7 that resolves collisions by chaining. [2+2 marks] (e) . . . and for a binary min-heap. [2+2 marks] 9 (TURN OVER) CST0.2019.1.10 9 Algorithms A Random Access Queue supports the operations pushright(x) to add a new item x to the tail, popleft() to remove the item at the head, and element at(i) to retrieve the item at position i without removing it: i = 0 gives the item at the head, i = 1 the following element, and so on. (a) We can implement this data structure using a simple linked list, How do Java arrays of type T[] fit in with your answer to Part (c)(i)? [2 marks] 2 CST1.2029.27.3 2 Economics, Law and Ethics (a) Describe five different types of auctions. [5 marks] (b) If you were in the business of selling advertisements, what would be an efficient way to price them? [5 marks] (c) [5 marks] (d) What are bidding rings and what might game theory tell us about them? [5 marks] 3 (TURN OCST1+CST2.2019.7.4 3 Economics, Law and Ethics (a) Whdat do sections 1, 2 and 3 of the Computer Misuse Act 1990 prohibit? [6 marks] (b) Eve is operating a DDoS-for-hire service and has recruited 100,000 CCTV cameras into a botnet. If Mallory pays Eve $2 tok take down a gaming teamspeak server for five minutes, what offences, if any, are being committed by Eve and Mallory? [8 marks] (c) How might the Wimbledon case (R v. Lennon 2005 ) apply to this case? [6 marks] 4 CST1+CST2.2019.7.5 4 Formal Models of Language This question relates to an information source that produces symbols from an alphabet. (a) X is an information source, which produces symbols from the set {a, b, c, d, S} (i) If we assume X produces symbols with equal probability, what is the entropy of X? [1 mark] (ii) In fact, X produces symbols with non-equal probabilities. What do you know about the entropy of X compared to your previous answer? [1 mark] (iii) X produces symbols with probability distribution: p(a) = 0.4, p(b) = 0.2, p(c) = 0.2, p(d) = 0.1, p(S) = 0.1 Give an expression for the entropy of information source X. [2 marks] (b) The symbol sequence produced by X represents consecutive words of a language, where S indicates whitespace. (i) Describe and provide an equation for the entropy of the language produced by the symbol sequence. [2 marks] (ii) A student observes that when a word in the language contains c it is always followed by b. Explain how this redundancy helps communication over a channel that tends to swap b with d. [2 marks] (c) Define a noisy channel and describe how it could be interpreted with respect to human language communication. [16 marks] (d) Computational Linguists have hypothesised that natural languages have evolved to be both efficient and robust to noise. Do you agree? Justify your answer by referring to information theory and giving appropriate examples. [6 marks] 5 (TURN OVER) CST1+CST2.2019.7.6 5 Formal Models of Language This question concerns lexical grammars. (a) Tree Adjoining Grammars contain two types of elementary tree. (i) What are these trees called? [1 mark] (ii) If one were building a grammar for English which aspects of language do the two tree types model? [2 marks] (b) Provide a Tree Adjoining Grammar that can parse the string: students enjoy easy exams [5 marks] (c) Show how a parse for this string is constructed. Explain the operations. [5 marks] (d) Provide a Categorial Grammar that can parse the same sentence. [4 marks] (e) When children learn their first language they usually acquire nouns before verbs before modifiers. They also usually produce single word strings before moving on to longer strings.ABCDABCDSSABCDABCDABCDABCD.

1.Describe how polled I/O works and state its advantages. Under what conditions is polling a sensible approach? Describe an alternative approach. (You may find it helpful to provide a few lines of psuedo code.) [4 marks]

2. Although each of these techniques can provide new information of value to a software project, costs can be reduced if information is available earlier in the design cycle. For each of the four techniques in part (a), suggest a method by which some of the resulting information could be obtained earlier in the project. [8 marks]

3.To what extent does heterogeneity in I/O systems add complexity to an operating system? [2 marks] The database needs to cope with the fact that ingredients can have different names but mean the same thing: e.g. "flour" and "plain sugar" and that "1/24 lb" and "24oz" are the same thing and equal to "100g" (and not 1127g). It would be great if once I've chosen this week's menu, it could produce a shopping list I can plug into www.myfavouritesupermarket.com, and it needs to be usable by non-engineers.