ABSTRACT
The Appalachian Trail (AT), a 2,160-mile footpath from Georgia to Maine in the eastern US, has a series of lean-to shelters. Suppose we backpack on the AT and plan to spend the night at Rocky Gap Shelter. We’d like to know beforehand whether there’s water (a spring or stream) close by. If we knew that all AT shelters have water, or that none do, we could reason deductively:
All AT shelters have water. Rocky Gap is an AT shelter. Á Rocky Gap has water.
