hornface

@hornface@fedia.io

• ⁨Comment⁩ on ⁨Is "If A then B" equal to "B if and only if A"?⁩ ⁨⁨10⁩ ⁨months⁩ ago⁩:

  "if and only if" is an unusual and sometimes confusing way to say it, but the words do directly imply the technical definition.

  "it's an apple if and only if it's a fruit" literally means "it's an apple if it's a fruit" and "it's an apple only if it's a fruit". You already seem to understand the 2nd part, so no need to explain that.

  The first part is a bit confusing because the words are in the reverse order compared to how people normally talk. "it's an apple if it's a fruit" means the same thing as "if it's a fruit, then it's an apple". Clearly "if it's a fruit, then it's an apple" is not a true statement, because there are plenty of other fruits apart from apples.