Some problematic, simple, narrative structures

 In my theory of "verbs", I take them to be action events, with an actor acting on a target and changing it. For the action X->Y, we name the change in Y, as dY/dX(v), where v is a particular action. There is also a Newton's Law saying that actions always change targets, and targets are only changed by an action. I should add that my handling of intransitive verbs like: "The dog is running" says that they are describing an attribute relation, no different from saying "The dog has fur". So we might write dog_/running.

So I have a couple problems with these concepts. Here are sentences where the action is unclear but the transition is described. Are these changes or actions?

1. The bubble pops

2. The dog barks

3. The fruit rots.

Now, I think we can take 2 as dog_/barking. But 1 and 3 involve changes to the object without an action causing it - seemingly a violation of "Newton's Law". 

But how about if we treat all of these as the changes brought about by an implicit action? So [X]->bubble becomes bubble_/pops, [X]->dog becomes dog_/barking, and [X]->fruit becomes fruit_/rotting. Are these implicit actions or changes? I hope it doesn't matter but it would be nice to get straight.