The Company XYZ has 1173 blocks of building for its business operation, where each block has 7 floors. The distance between each floor is 7 meters. ] (ii) Give a function run2diff which can be applied to your answer to part (c)(i). When so applied it should give a value in the IO monad which corresponds to ML code that runs add1 twice and returns the difference between the values read. [4 marks] (d) State what happens when attempting to compile and execute the following Java fragment (explaining the origin of any error messages or exceptions which might arise). Object n = new Integer(42), o = new String("Whoops"); Object [] v; Integer [] w = new Integer[10]; v = w; v[4] = n; v[5] = o; [4 marks] (e) Consider the Java code: Object n = new Integer(42); ArrayList v1; ArrayList v2; ArrayList w = new ArrayList<>(10); Explain any differences in behaviour between assignments v11 = w and v2 = w and also between method calls v1.set(14,n) and v2.set(4,n). [4 marks] 16 CST.2016.3.7 6 Further Java (a) Describe the operation of wait() and notifyAll(). Ensure that your answer explains when locks are acquired and released. [5 marks] (b) A future is a mechanism to store the eventual result of a computation done in another thread. The idea is that the computation is run asynchronously and the calling thread only blocks if it tries to use a result that hasn't been computed yet. An example program using a future is shown below. Future f = new Future() { @Override public String execute() { // ...long running computation... return data; }; // ... String result = f.get(); // blocks if execute() unfinished Use wait() and notifyAll() to provide an implementation of the Future class that would work with the example program above. [10 marks] (c) Give one potential advantage and one potential disadvantage of using notify() instead of notifyAll(). [2 marks] (d) Would it have been beneficial to use notify() instead of notifyAll() in your implementation? Justify your answer. [3 marks] 17 (TURN OVER) CST.2016.3.8 17 Prolog In this question you should ensure that your predicates behave appropriately with backtracking and avoid over-use of cut. You should provide an implementation of any library predicates used. You may not make use of extra-logical built-in predicates such as findAll. Minor syntactic errors will not be penalised. (a) Rewrite chooseAll without using not and cut (!). [10 marks] chooseAll(N,L,Res) :- chooseAll(N,L,[],Res). chooseAll(N,L,Seen,Res) :- choose(N,L,R), not(member(R,Seen)), !, chooseAll(N,L,[R|Seen],Res). chooseAll(,,Res,Res). (e) What is Last Call Optimisation and why is it beneficial? [3 marks] (f ) Rewrite pos to enable Last Call Optimisation. [2 marks] pos([],[]). pos([H|T],[H|R]) :- H >= 0, pos(T,R). pos([H|T],R) :- H < 0. Consider different versions of an optimising compiler, each of which uses IEEE standard representation for all variables. Give two reasons why they might compile a floating-point program into code that, when run, produces differing results. [2 marks] 6 CST.2016.1.7 6 Numerical Methods A picnicker brings hot black coffee and cold milk in two identical insulated flasks and then mixes them for his drink. His friend claims that the drink would have ended up the same temperature if he had mixed the two at home and brought one flask. Note: The temperature of an object is the heat energy within it divided by its heat capacity. The rate of heat energy flow from a hotter to a cooler object is their temperature difference divided by their insulation resistance. When two fluids are mixed the resultant temperature is the sum of their initial temperatures weighted by their proportions. (a) Give a suitable state vector for a simple, finite-difference, time domain simulation of the drink system. [3 marks] (b) List the initial values and any other parameters that are needed for the simulation. TLBs and caches are examples of content-addressable memories (CAMs). (a) What is the principal difference between a CAM and a RAM? [4 marks] (b) What is the difference between fully associative, set associative and direct mapped lookup? [6 marks] (c) Why are TLBs always much smaller than caches? [4 marks] (d) Which of the lookup mechanisms in part (b) is usually used for a TLB and why aren't the other mechanisms usually used? [6 marks] 2 ECAD Consider the following mysterious Verilog module. module mystery(c,r,a,s); input c,r,a; output [2:0] s; reg [2:0] s; always @(posedge c or posedge r) if(r) s<=0; else begin if(a && (s<7)) s<=s+1; else if(!a && (s>0)) s<=s-1; end endmodule (a) How many flip-flops will be required to implement the mystery module, and how will signals c and r be connected to these flip-flops? [5 marks] (b) What is the state transition diagram for this mystery module? [5 marks] (c) If this module were synthesised to the minimum sum of products form, what would the equations be for next state bits s[0], s[171] and s[172]? [110 marks] 2 CST.21047.1.3 3 Data Structures and Algorithms (a) Describe how the Lempel Ziv text compression algorithm works, illustrating your answer by deriving the sequence of numbers and corresponding bit patterns it would generate when applied to a string starting with the following 24 characters: ABCDABCDABCDABCDABCDABCD ... You may assume that the initial table is of size 256 (containing bytes 0 to 255) and that the codes for "A", "B", "C" and "D" are 65, 66, 67 and 68, respectively. [12 marks] (b) Estimate how many bits the algorithm would use to encode a string consisting of 1000 repetitions of the character "A". [8 marks] 4 Comparative Programming Languages (a) Discuss to what extent a programmer can expect a program that conforms to a standard to generate identical results when run under different conforming compilers on different machines. [16 marks] (b) ALGOL 60 provided call by value and call by name, Pascal provided call by value and call by reference, and ALGOL-W provided a variety of calling methods including call by result and call by value-result. Briefly describe the calling mechanisms just mentioned and discuss why most modern programming languages provide only call by value. [18 marks] (c) Discuss the reasons why languages such as Fortran, Algol and PL/I designed in 1950s and 1960s are less widely used than languages designed in the last 20 years. [6 marks] 3 [TURN OVER CST.2004.3.4 5 Operating Systems II (a) What problem do real-time scheduling algorithms try to solve? [2 marks] (b) Describe one static priority and one dynamic priority real-time scheduling algorithm. You should discuss the issue of admission control, and comment on the data structures that an implementation would need to maintain and on how these would be used to make scheduling decisions.are a data structure protected by a mutual exclusion lock. (i) What scheduling problem could arise here? [2 marks] (ii) How could this problem be overcome? [2 marks] (d) The designer also wishes the real-time system to use demand paged virtual memory for efficiency. With the three datasets you have decided to use multiple tools in your Hadoop environment, an external hive table called "Company" in the default database using Company_data.csv , use a separate folder for file in HDFS. After Completing your hive table make sure you can access it, secondly upload the Company_Emp_data.csv and the Sales_data.csv to a HDFS folder. Write brief notes on functions as values and results in ML, illustrated with the help of the functionals map and exists. What functions can we obtain from these via currying? [6 marks] (b) Consider the function zarg defined below: fun zarg f ([], e) = e | zarg f (x::xs, ee) = f(x, zarg f (xs,eee)); Show that with the help of this function, it is possible to an expression for the sum of a given list of integers. Then describe what zarg does in general. [4 marks] (c) A polymorphic type of branching trees can be declared as follows. Note that the children of a branch node are given as a list of trees, and that only the leaf nodes carry labels. datatype 'a vtree = Lf of 'a | Br of ('a vtree) list; (i) Write function flat t that converts a given tree t of this type to a list of the labels (without eliminating duplicates). Your function should run in linear time in the size of the tree. [4 marks] (ii) Write function counts x t that counts the number of times that x occurs as a label in t, but without first converting t to a list. Part 1: We have now established a Hive table "products" and threeSpark Dataframe SQL accessible views "Salesworth" and "Empview" we are now in a position to provide some analysis on Mrs adebabamo's ask. Give a brief and rudimentary clarification of the standards of how the language. coming about because of part (b) may be utilized to a sentence structure analyser taking a token stream as information (by means of calls to work lex()) and giving as result an theoretical language structure tree relating to. (a) What is the principal difference between a CAM and a RAM? [4 marks] (b) What is the difference between fully associative, set associative and direct mapped lookup? [6 marks] (c) Why are TLBs always much smaller than caches? [4 marks] (d) Which of the lookup mechanisms in part (b) is usually used for a TLB and why aren't the other mechanisms usually used? [6 marks] 2 ECAD Consider the following mysterious Verilog module. module mystery(c,r,a,s); input c,r,a; output [2:0] s; reg [2:0] s; always @(posedge c or posedge r) if(r) s<=0; else begin if(a && (s<7)) s<=s+1; else if(!a && (s>0)) s<=s-1; end endmodule (a) How many flip-flops will be required to implement the mystery module, and how will signals c and r be connected to these flip-flops? 15 marks] (b) What is the state transition diagram for this mystery module? [5 marks] (c) If this module were synthesised to the minimum sum of products form, what would the equations be for next state bits s[0], s[1] and s[2]? [10 marks] 2 CST.2004.3.3 3 Data Structures and Algorithms Compiler Construction Programming answers should be written in some notation approximating SML or OCaml. (a) Describe what is meant by tail recursion. [4 marks] (b) Eliminate tail recursion from foldl given below. Consider different versions of an optimising compiler, each of which uses IEEE standard representation for all variables. Give two reasons why they might compile a floating-point program into code that, when run, produces differing results. [2 marks] 6 CST.2016.1.7 6 Numerical Methods A picnicker brings hot black coffee and cold milk in two identical insulated flasks and then mixes them for his drink. His friend claims that the drink would have ended up the same temperature if he had mixed the two at home and brought one flask. Note: The temperature of an object is the heat energy within it divided by its heat capacity. The rate of heat energy flow from a hotter to a cooler object is their temperature difference divided by their insulation resistance. When two fluids are mixed the resultant temperature is the sum of their initial temperatures weighted by their proportions. (a) Give a suitable state vector for a simple, finite-difference, time domain simulation of the drink system. [3 marks] (b) List the initial values and any other parameters that are needed for the simulation. c) Suppose that the following rules are proposed as possible optimizations to be implemented in your compiler. expression simplifies to expression (fst e, snd e) e fst (e1, e2) e1 snd (e1, e2) e2 Describe how you could implement these rules so that the simplifications are made only when the program's semantics is correctly preserved. [5 marks] 5 (TURN OVER) CST.2016.3.6 5 Concepts in Programming Languages (a) Explain what is meant by a monad in a programming language, giving the two fundamental operations of a monad along with their types. [3 marks] (b) Consider the use of a monad for input-output. For the purposes of this question, take the IO monad as including two operations readint and writeint which respectively read integers from stdin and write integers to stdout. Give the types of these operators. [2 marks] (c) Assume MLreadint and MLwriteint are primitives with side effects for inputoutput and consider the ML expression add1 of type int: let val x = MLreadint() in MLwriteint(x+1); x end (i) Give an equivalent expression which uses the IO monad instead of side-effects, and state its type. [3 marks] (ii) Give a function run2diff which can be applied to your answer to part (c)(i). When so applied it should give a value in the IO monad which corresponds to ML code that runs add1 twice and returns the difference between the values read. [4 marks] (d) State what happens when attempting to compile and execute the following Java fragment (explaining the origin of any error messages or exceptions which might arise). Object n = new Integer(42), o = new String("Whoops"); Object [] v; Integer [] w = new Integer[10]; v = w; v[4] = n; v[5] = o; [4 marks] (e) Consider the Java code: Object n = new Integer(142); ArrayList v1; ArrayList v21; ArrayList w = new ArrayList<>(110); Explain any differences in behaviour between assignments v1 = w and v2 = w and also between method calls v1.set(4,n) and v2.set(4,n). [4 marks] 6 CST.2016.3.7 6 Further Java (a) Describe the operation of wait() and notifyAll()