no X builds Y but not Z

Comments

• 1 Like

  jdawg113 Alum Inactive ⭐

  February 2015 2654 karma

  if Y & /Z -> /x (i think)lol took me a minute to make sense of that, its saying X cannot build Y without building Z too
• Alex Short Alum Member

  February 2015 112 karma

  Hey Alex - how's it going? Long time no see - we should meet up sometime. I would look at this statement as "X builds Y, but not Z", with the 'No' negating all elements that follow.
  
  I understand "X builds Y, but not Z" much more easily, and would write it as a single X with two arrows, one to Y and another to ~Z.
  
  If there is no comma in the statement, I'd have to assume the "No" at the beginning applies to both elements.
  
  So, "No X builds Y":
  X -> ~Y
  
  And "No (X builds Not Z)"
  (X -> ~Z)
  ~X -> Z
  
  Ultimately getting:
  
  X -> ~Y and ~X -> Z
  
  Although, admittedly, I'm certainly uncertain about my approach in this case.
• Alex Short Alum Member

  February 2015 112 karma

  jdawg's approach was the other route I imagined possible... but I hesitated with that approach only because the grammar trips me up with this particular phrasing (aka, the lack of a comma). Good to know!
  
  
• jdawg113 Alum Inactive ⭐

  February 2015 2654 karma

  @"Alex Short" idk, that makes it look like X can't build Y and Z which isn't how I see it. I see it as X can build Y and Z but cannot build Y if it doesnt also build Z
• Alex Short Alum Member

  February 2015 112 karma

  @jdawg113 Okay, that makes much more sense for me - I saw both as possibilities but I thought that
  
  "X can build Y and Z but cannot build Y if it doesnt also build Z"
  
  would be written as "No X builds Y, but not Z". And with that, time for some coffee! Thanks for the clarification though; I appreciate it!
• Catehm88 Alum Member

  February 2015 edited February 2015 8 karma

  It is saying that if X builds Y, then it must also build Z take out the negative language on this one.
  
  (X-->Y)--> (X-->Y&Z)
  
  The contrapositive of the statement is, if X does not build Z then it does not build Y.
  
  I hope this helps a little.
  
• jdawg113 Alum Inactive ⭐

  February 2015 2654 karma

  eh its similar... and I like the wording you used there @Catehm88
• blah170blah Alum Inactive ⭐

  February 2015 3545 karma

  Wait, I'm actually confused lol. I understood this statement to mean two things:
  1) no X builds Y (Y --> /X)
  2) no X does not build Z ( Z --> X)
  
  Y --> /X
  /X --> /Z
  -----------
  Y --> /Z
  
  Is that not right? lol
  
  
• jdawg113 Alum Inactive ⭐

  February 2015 2654 karma

  @blah170blah I don't think so. think of it as no X builds Y without(but not) building Z
• blah170blah Alum Inactive ⭐

  February 2015 3545 karma

  Ahhh I see. So we have two conditions for the conditional.
  
  If you have Y AND /Z then you don't have /x.
  
  Which is what you said:
  Y & /Z ---> /X
• Matt1234567 Inactive ⭐

  February 2015 1294 karma

  I take it as If it is X and it builds Y, it must build Z.
• jdawg113 Alum Inactive ⭐

  February 2015 2654 karma

  @Matt1234567 yes