e SRAM banks be efficiently interconnected so that the cache's access time is constant regardless of which bank is accessed? [4 marks] (d) Why might it be advantageous to be able to manage the amount of LLC used by each co-scheduled thread in a chip multiprocessor? [5 marks] 8 CST.2016.7.9 7 Denotational Semantics (a) (i) Define the notion of continuous function between domains. [2 marks] (ii) Let P(N 2 ) be the domain of all subsets of pairs of natural numbers ordered by inclusion. Show that the function f : P(N 2 ) ? P(N 2 ) given by f(S) = { (1, 1) } ? { (x + 1, x y) ? N 2 | (x, y) ? S } (S ? N 2 ) is continuous. [3 marks] (b) (i) State Tarski's fixed point theorem for a continuous endofunction on a domain. [2 marks] (ii) Give a concrete explicit description of the fixed point fix (f) ? N 2 of the continuous function f in Part (a)(ii). Briefly justify your answer. [3 marks] (c) (i) Define the notion of an admissible subset of a domain. [2 marks] (ii) Let P ? P(N 2 ) be defined as P = { S ? N 2 | ? (x, y) ? S. log y ? xlog x }. Show that P is an admissible subset of the domain P(N 2 ). [3 marks] (d) (i) State Scott's fixed point induction principle. [2 marks] (ii) Use Scott's fixed point induction principle to show that fix (f) ? P for f the continuous function in Part (a)(ii) and P the admissible subset of the domain P(N 2 ) in Part (c)(ii). [3 marks] 9 (TURN OVER) CST.2016.7.10 8 Hoare Logic and Model Checking This question considers a language L which has integer variables V , arithmetic expressions E and boolean expressions B, along with commands C of the forms V :=E (assignment), C; C 0 (sequencing), IF B THEN C ELSE C 0 (conditional) and WHILE B DO C (iteration). (a) Explain the syntax of the Hoare-logic partial-correctness formula {P} C {Q} and give a careful definition in English of when it is valid, that is, when |= {P} C {Q}. [2 marks] (b) How does the definition of validity for the total-correctness formula [P] C [Q] differ? [1 mark] (c) Preconditions and postconditions in {P} C {Q} often make use of logical or auxiliary variables v in addition to program variables V . Explain why this is useful illustrating your answer with a command C which satisfies {T} C {R = X + Y} but not {X = x ? Y = y} C {R = x + y}.

(a) Give three methods of computing location of cell phones and indicate the accuracy in each case. [10 marks] (b) What is the location accuracy of GPS (Global Positioning System) and how can it be improved? [5 marks] (c) Give the accuracy of the ultrasonic Active Bat location system and discuss how it might compare with radio-based ultra wideband location systems. [5 marks] 15 Additional Topics (a) In relation to the locational privacy problem for the Active Badge system: (i) Define location privacy. (ii) Define a sensible security policy for the system with respect to location privacy. (iii) What elements of the system does a user need to trust? (iv) What if one does not want to be tracked? [6 marks] (b) In the Active Badge system, the badge emits its identifier and the building infrastructure picks it up. To protect location privacy, some have suggested to reverse this architecture: the room would transmit its identifier and the badge would pick it up. Discuss advantages and disadvantages of this arrangement. [2 marks] (c) You are required to design the security architecture for a location-based system. You are the cellular phone operator, so you know the location of users; application providers selling their location-based services to users must go through you. Of course you know the position of all active phones at all times, but you want to reassure your users that application providers can't track them. State your security policy and describe your implementation that enforces it. [6 marks] (d) Describe at least two attacks against the system you designed in part (c).

(a) Compare and contrast each of the following techniques for achieving instruction-level parallelism: (i) statically-scheduled super scalar; (ii) out-of-order speculative execution; (iii) Very Long Instruction Word (VLIW); (iv) EPIC (as used by IA-64). [12 marks] (b) Discuss hardware multi-threading, and hence the different implementation approaches that have been tried to enable a single CPU core to execute from multiple instruction streams. How can multi-threading be used to improve system performance? What are the pitfalls? [8 marks] 2 Digital Communication II (a) Explain the terms Work Conservation and max-min fairness, in the context of packet switching. [8 marks] (b) Outline the operation of two work-conserving queueing schemes that provide max-min fairness, and two (simpler) ones that do not. [8 marks] (c) Give at least two main implementation costs associated with implementations of fairness in packet switched routers. [4 marks] 3 Security (a) Describe the Bell-LaPadula security policy. [6 marks] (b) Describe the Chinese Wall security policy. [6 marks] (c) To what extent is the Chinese Wall policy an extension of Bell-LaPadula? [6 marks] (d) Are either of these policies relevant to digital rights management? [2 marks] 2 CST.2003.7.3 4 Advanced Graphics (a) We want to find the first intersection point between an arbitrary ray and a sphere of arbitrary radius at an arbitrary position in space. (i) List and define all of the parameters required to specify the geometry of the ray and the sphere. [2 marks] (ii) Give an algorithm which returns the desired intersection point (if it exists) and the appropriate normal vector at the intersection point. [5 marks] (b) Describe a method which converts an arbitrary sphere to a triangle mesh at a desired resolution. The desired resolution is specified as a desired number of triangles, D. Your method should produce a number of triangles, N, which is within an order of magnitude of D: D/10 < N < 10D. [4 marks]

Let N(t) denote the number of events in the time interval [0, t] for a (homogeneous) Poisson process of rate ?, (? > 0). (a) State the necessary properties on N(t) that define a (homogeneous) Poisson process of rate ?. [4 marks] (b) By dividing the interval [0, t] into equal length sub-intervals show that N(t) is a Poisson random variable with mean ?t. [4 marks] (c) Let X1 denote the time of the first event and for n > 1 let Xn denote the elapsed time between the (n ? 1)th and the nth events of the Poisson process. Determine the distribution of X1 and the joint distribution of X1 and X2. [4 marks] (d) Let Sn = Pn i=1 Xi denote the time of the nth event. Derive the probability density function of the random variable Sn(t). [4 marks] (e) Give an algorithm to generate the first T time units of a (homogeneous) Poisson process of rate ?. [4 marks] 6 Specification and Verification I (a) Explain the difference between a variant and an invariant. Briefly describe what they are used for. [4 marks] (b) State and justify the verification conditions for the total correctness of WHILE commands. [6 marks] (c) (i) Devise a precondition P that makes the following specification true. [P] WHILE I?N DO SUM := SUM+(2I); I := I+1 [SUM = N(N+1)] [2 marks] (ii) Devise and justify annotations for this specification that yield provable verification conditions.

CoursHeroTranscribedText

Transcribed Image Text:

Create a Graphical User Interface that has two buttons and a textArea (See Examples 12.3 and Example 12.4). figure 1 Create a String array to store the following messages (Enter your name where it says YourName). "Congratulations YourName!nYou completed the Java class. nYou learned to write Java programs with commonly usedn control structures." "Congratulations YourName!nYou completed the Java class. nYou learned to create a Java program using classes and methods." "Congratulations YourNameInYou completed the Java class. nYou learned to create an Applet to draw shapes using graphics nmethods." *Congratulations YourName!nYou completed the Java class. nYou learned to develop Java program using arrays." "Congratulations YourName!nYou completed the Java class. nYou learned to write a Java program using sorting techniques." "Congratulations YourName!nYou completed the Java class. nYou learned to code a Java program where parameters are passed." "Congratulations YourNameInYou completed the Java class. nYou learned to identify and correct program errors." To determine which message is displayed, you will use a random number between 0 and 6 (see page 125 or Example 3.8). The random number will determine the index of the array message to display in the JTextArea. When the clear button is pressed, the JTextArea message is equal to "This is where it will display what I learned.nMessage Displayed Here." figure 2 The layout style will be a FlowLayout. Set the size of display screen to 400 by 200 [setSize(400, 200):] Create a Graphical User Interface that has two buttons and a textArea (See Examples 12.3 and Example 12.4). figure 1 Create a String array to store the following messages (Enter your name where it says YourName). "Congratulations YourName!nYou completed the Java class. nYou learned to write Java programs with commonly usedn control structures." "Congratulations YourName!nYou completed the Java class. nYou learned to create a Java program using classes and methods." "Congratulations YourNameInYou completed the Java class. nYou learned to create an Applet to draw shapes using graphics nmethods." *Congratulations YourName!nYou completed the Java class. nYou learned to develop Java program using arrays." "Congratulations YourName!nYou completed the Java class. nYou learned to write a Java program using sorting techniques." "Congratulations YourName!nYou completed the Java class. nYou learned to code a Java program where parameters are passed." "Congratulations YourNameInYou completed the Java class. nYou learned to identify and correct program errors." To determine which message is displayed, you will use a random number between 0 and 6 (see page 125 or Example 3.8). The random number will determine the index of the array message to display in the JTextArea. When the clear button is pressed, the JTextArea message is equal to "This is where it will display what I learned.nMessage Displayed Here." figure 2 The layout style will be a FlowLayout. Set the size of display screen to 400 by 200 [setSize(400, 200):]