> Your example of "what's the shortest path between two points" is such an example: the decision variant is "is there a path between two points less than k?"

> Your example of "what's the shortest path between two points" is such an example: the decision variant is "is there a path between two points less than k?" Just to add to this: This can obviously also be brought back to "find the shortest path", by just asking the question again and again for smaller and smaller k, by halving.