title: Theory: Compression algorithm that makes some files smaller but none bigger?
body: <p>I came across this question;</p>
  <p>&quot;A lossless compression algorithm claims to guarantee to make some files smaller and no files larger. <br>
  Is this;</p>
  <blockquote>
  <p>a) Impossible</p>
  <p>b) Possible but may run for an indeterminate amount of time,</p>
  <p>c) Possible for compression factor 2 or less,</p>
  <p>d) Possible for any compression factor?&quot;</p>
  </blockquote>
  <p>I'm leaning towards (a), but couldn't give a solid explanation as to why. (I'll list the thoughts a friend and I came up with as a possible answer)</p>