Recall that Reach is the problem of deciding, given a graph G a source vertex s and a target vertex t, whether G contains a path from s to t; and Sat is the problem of deciding whether a given Boolean formula is satisfiable. For each of the following statements, state whether it is true or false and justify your answer. (i) If Reach is NP-complete then P=NP. [3 marks] (ii) If Reach is NP-complete then NP6=PSPACE. [3 marks] (iii) If Sat is PSPACE-complete then NP=PSPACE. (f ) Summarize any issues connected with left-or right-cooperative administrators in the two methods (in executing the parser and in developing the apparatus) you illustrated to some degree (e). Give two different ways of implementing residual information protection in an operating system and explain the threat addressed by each. [5 marks] (c) Consider the standard POSIX file-system access control mechanism: (i) Under which conditions can files and subdirectories be removed from a parent directory? [2 marks] (ii) Many Unix variants implement an extension known as the "sticky bit". What is its function? [2 marks] (iii) On a POSIX system that lacks support for the "sticky bit", how could you achieve an equivalent effect? [2 marks] (d) VerySafe Ltd offer two vaults with electronic locks. They open only after the correct decimal code has been entered. The solutions in parts (a) and (b) both involve a get() method returning an Object reference. (i) Explain why this is bad practice. [1 mark] (ii) Propose an alternative solution for a constrained array of Integer or LinkedList objects (only) that addresses this issue. [5 marks] 4 CST.2016.1.5 4 Object-Oriented Programming (a) Using example Java code, distinguish between overloading, overriding and shadowing when applied to Java methods. Describe a sequence of events that would allow external modification of an object stored within an IntListArray, despite correct copying on insertion. How could this be addressed in IntListArray? [3 marks] (iii) By adding protected void add(Object o) {mArray.add(o);} to the ConstrainedArray class, the mArray field can be made private. Show how this would affect your IntListArray class and discuss the advantages of the change from protected to private. [5 marks] (c) The solutions in parts (a) and (b) both involve a get() method returning an Object reference. (i) Explain why this is bad practice. [1 mark] (ii) Propose an alternative solution for a constrained array of Integer or LinkedList objects (only) that addresses this issue. [5 marks] 2 Hosts 50/1/1 S0/1/0 R1 R2 GOM S2 PC2 GO1 50/1/1 NW:10.10.100.0/24 50/170 Network P: 15 Hosts Network Q: 10 Hosts Network Z: 2 Hosts Network Y: 2 Hosts 50/110 50/1/1 R3 G0/1 Network R: 4 Hosts 53 PC3 Part 1: Design the VLSM Address Scheme Divide the 10.10.100.0/24 network based on the number of hosts per subnet and complete the Subnet Table. You will subnet the network address 10.10.100.0/24. The network has the following requirements: Network P (LAN) requires 15 Usable host IP addresses. (Use the third available subnet) Network Q (LAN) requires 10 Usable host IP addresses. (Use the next available subnet) Network R (LAN) requires 4 Usable host IP addresses. (Use the next available subnet) Network X (WAN) requires 2 Usable host IP addresses. (Use the next available subnet) Network Y (WAN) requires 2 Usable host IP addresses. (Use the next available subnet) Network Z (WAN) requires 2 Usable host IP addresses. (Use the next available subnet) Subnet Table: Subnet Description Network Address First Host Address Second Host Address Last Host Address Broadcast Address Subnet Mask Network P Network Network R Network X NA Network Y NA Network Z NA Part 2: Complete the Addressing Table Document the addressing scheme and complete the addressing table. a. Assign the Last host IP address from Network P subnet to G0/1 interface of Ri. b. Assign the First host IP address from Network P subnet to Sl. c. Assign the Second host IP address from Network P subnet to PCI. d. Assign the Last host IP address from Network Q subnet to GO/1 interface of R2. e. Assign the First host IP address from Network Q subnet to S2. f. 4 CST.2016.1.5 4 Object-Oriented Programming (a) Using example Java code, distinguish between overloading, overriding and shadowing when applied to Java methods. (e) Give a brief and rudimentary clarification of the standards of how the language coming about because of part (b) may be utilized to make 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 part (d). Two major activities of the software design process include Software Architecture and Detailed Design. Demonstrate on how these two activities being executed? Do you design software when you "write" a program? What makes software design different from coding?