Couple of thoughts: First, the discussion about representation highlights that the issue is a lack of infinite resources. If we had an infinite computer, that

Couple of thoughts: First, the discussion about representation highlights that the issue is a lack of infinite resources. If we had an infinite computer, that could execute an infinite number of operations in zero time, and had infinite memory, then we wouldn't be worrying about whether it's better to store the graph as a matrix, an edge list, or a pointer graph. Software Engineering is everywhere and always a job of optimization. Sometimes that optimization is premature, and sometimes it's too little too late. It's always about optimization. Second, when we're talking about a graph of 10 nodes, it really doesn't matter what data structure we use. It can quickly matter if we have 100s or 1000s of nodes and edges because now the possible arrangements are huge as is the search space. But this is no different than other problems like the knapsack problem where the search space is huge: depending on the problem, there is very likely a "trick" to make it tractable, and that trick is different depending on the problem. So, like the knapsack problem, there are different, specific solutions for specific graph problems.