title: Type Error in Alloy using Double In Statement
body: <p>I am trying to write a predicate that will make all Bananas and Fresh Apples expensive. I am able to achieve one of the conditions but never both. I'm very new to using Alloy, any help would be very much appreciated. </p>
  
  <p>Below is my code, the error is occurring because I'm using a double In Statement but I'm unsure how I could write this without having to use two in statements. The error I receive is "Type Error, this must be a set or relation"</p>
  
  <pre><code>sig Fruit{}
  sig Banana, Apple, Pear extends Fruit {}
  sig Fresh, Expensive in Fruit{}
  
  pred BananasAndFreshApplesAreExpensive {
  Apple in (Expensive &amp; Fresh) + Banana in Expensive
  } 
  run BananasAndFreshApplesAreExpensive
  </code></pre>