title: PDDL - Using numeric fluents using solver.planning.domains
body: <p>I'm a noob at planning and I'm looking for help with numeric fluents.  Here's a sample domain and problem that isn't working the way I think it should.</p>
  
  <p>Domain:</p>
  
  <pre><code>(define (domain tequila)
    (:requirements :typing :fluents)
    (:types
      bottle
      )
    (:functions
      (amount ?b - bottle)
      )
    (:predicates
      (bottle-finished ?b - bottle)
      )
  (:action drink
    :parameters (?b - bottle)
    :precondition (&gt;= (amount ?b) 1)
    :effect (decrease (amount ?b) 1)
    )
   (:action done-drinking
   :parameters (?b - bottle)
   :precondition (= (amount ?b) 0)
   :effect (bottle-finished ?b)
   )
  )
  </code></pre>
  
  <p>and the problem:</p>
  
  <pre><code>(define (problem drink)
    (:domain tequila)
    (:objects
      casamigos-anejo - bottle
    )
    (:init
      (= (amount casamigos-anejo) 4)
    )
    ; drink all the tequila
    (:goal
      (bottle-finished casamigos-anejo) 
    )
  )
  </code></pre>
  
  <p>I'm running the files using editor.planning.domains.  I expected that the plan would be "drink, drink, drink, drink, done-drinking" but the plan it finds is just "done-drinking".  Can someone explain if I'm doing something wrong, or if it's working correctly and my expectation is wrong (I'm sure I'm thinking of it in procedural terms)?  Thanks.</p>