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← 21-07 Functional Properties Solution

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Showing Revision 1 created 10/03/2012 by Amara Bot.

  1. The first one of course is not a functional property because condition two is not fulfilled.
  2. All computer programs are computer programs.
  3. There is no computer program that is not a computer program.
  4. Of course, this sounds a bit silly but it's actually
  5. the only example I could think of where this condition here is violated.
  6. A program always returns one already is a functional property.
  7. First of all, it describes how output relates to the input
  8. namely output doesn't care about the input and is always one
  9. and property two is also always satisfied.
  10. For example, there are computer programs that I could write that always return two
  11. and property two is fulfilled for all the other three as well, so I won't even mention it anymore.
  12. A program solves vertex cover?
  13. Yes, definitely that describes an input-output behavior, how output relates to the input.
  14. Is a computer a virus? I would say yes, this is a functional property.
  15. Now, it is a bit debatable if saying it is a computer virus
  16. already described sufficiently how the output relates to the input
  17. but I would say that probably any definition of a computer virus that you would give me
  18. would in some way describe what the computer virus is doing.
  19. So, it might ignore anything that receives and overwrite your hard disc,
  20. so put something in the memory, or it might lock your screen.
  21. So, I would say here, the input-output behavior is variable
  22. depending on how you define computer virus but it is always defined.
  23. Now, the final one that is a bit of a tricky one saying that
  24. a program only requires linear time is not a functional property
  25. because that does not describe how the output relates to the input.
  26. It is the property of the program but it is not a functional property
  27. because it doesn't ask what does the program do
  28. and what does the program do is actually this relationship here.
  29. It only asked how fast that the program are doing that.
  30. This is something that is a little more tricky to figure out,
  31. but basically, any time that you ask can a program do X
  32. that will be a functional property that you are asking for
  33. at least in almost any of the cases.