"since 2009" is it inclusive or exclusive?

Solution 1:

Consider the sentence

Since earning a gold medal in the 2010 games, she has only earned silver medals and below.

This sentence exhibits behavior supporting the "exclusive" definition of "since". If it was the "inclusive" definition, her "gold medal in the 2010 games" would be included in her "only [earning] silver medals and below" which is logically impossible.

However, when referring to time alone there is evidence that the "inclusive" sense of "since" is more correct. Consider the sentence

Steve had been working since noon, and was famished.

Here it makes more sense to use the "inclusive" definition of "since", because using the "exclusive" definition directly implies that Steve began work after noon. Conventionally, the sentence means that Steve began work at noon.

Having provided both an exclusive and inclusive example, we can conclusively prove it ambiguous.