Think of the attacker as deriving the same utility whether he/she attacks Podunk 10 times, or Metropolis once. That's why the attacker is ready to attack Metropolis 10 times before occupying it, or Podunk once.
Likewise, the defender derives a utility of 10 for defending Metropolis and 1 from defending Podunk. What this means is that the defender is able to bear 9 blows from the enemy and it would still be worth it to defend Metropolis. After the 10th attack, the defender would derive the same utility from defending Metropolis as if he/she were to defend Podunk.
I hope that sorta explains it. Someone correct me if I got it wrong.
Think of the attacker as deriving the same utility whether he/she attacks Podunk 10 times, or Metropolis once. That's why the attacker is ready to attack Metropolis 10 times before occupying it, or Podunk once.
Likewise, the defender derives a utility of 10 for defending Metropolis and 1 from defending Podunk. What this means is that the defender is able to bear 9 blows from the enemy and it would still be worth it to defend Metropolis. After the 10th attack, the defender would derive the same utility from defending Metropolis as if he/she were to defend Podunk.
I hope that sorta explains it. Someone correct me if I got it wrong.