conciser validation

Author: JoviDeCroock

spec/Section 5 -- Validation.md

@@ -579,48 +579,32 @@ fragment conflictingDifferingResponses on Pet {
 
 Fragment spread arguments can also cause fields to fail to merge.
 
-While the following is valid:
-
 ```graphql example
 fragment commandFragment($command: DogCommand!) on Dog {
   doesKnowCommand(dogCommand: $command)
 }
 
 fragment potentiallyConflictingArguments(
   $commandOne: DogCommand!
-  $commandTwo: DogCommand!
 ) on Dog {
   ...commandFragment(command: $commandOne)
   ...commandFragment(command: $commandTwo)
 }
 
 fragment safeFragmentArguments on Dog {
-  ...potentiallyConflictingArguments(commandOne: SIT, commandTwo: SIT)
-}
-```
-
-it is only valid because `safeFragmentArguments` uses
-`potentiallyConflictingArguments` with the same value for the fragment-defined
-variables `commandOne` and `commandTwo`. Therefore `commandFragment` resolves
-`doesKnowCommand`'s `dogCommand` argument value to `SIT` in both cases.
-
-However, by changing the fragment spread argument values:
-
-```graphql counter-example
-fragment conflictingFragmentArguments on Dog {
   ...potentiallyConflictingArguments(commandOne: SIT, commandTwo: DOWN)
 }
 ```
 
-the response will have two conflicting versions of the `doesKnowCommand`
-fragment that cannot merge.
-
 If two fragment spreads with the same name supply different argument values,
 their fields will not be able to merge. In this case, validation fails because
 the fragment spread `...commandFragment(command: SIT)` and
 `...commandFragment(command: DOWN)` are part of the visited selections that will
 be merged.
 
+If both of these spreads would have `$commandOne` or `$commandTwo` as the argument-value,
+it would be allowed as we can be sure that we'd resolve identical fields.
+
 ### Leaf Field Selections
 
 **Formal Specification**