19 - Commonsense Reasoning
Published online by Cambridge University Press: 05 November 2011
Summary
Among the problems that have beset the field of artificial intelligence, or AI, two have a particularly logical flavor. One is the problem of nonmonotonicity referred to in Part I. The other is the so-called frame problem. In this lecture, we suggest that ideas from the theory presented here, combined with ideas and techniques routinely used in state-space modeling in the sciences, suggest a new approach to these problems.
Nonmonotonicity
The rule of Weakening implies what is often called monotonicity:
If Г ⊢ Δ then Г, α ⊢ Δ.
The problem of nonmonotonicity, we recall, has to do with cases where one is disinclined to accept a constraint of the form Г, α ⊢ Δ even though one accepts as a constraint Г ⊢ Δ. The following is an example we will discuss in this lecture.
Example 19.1. Judith has a certain commonsense understanding of her home's heating system – the furnace, thermostat, vents, and the way they function to keep her house warm. Her understanding gives rise to inferences like the following.
(α1) The thermostat is set between sixty-five and seventy degrees.
(α2) The room temperature is fifty-eight degrees.
⊢ (β) Hot air is coming out of the vents.
It seems that α1, α2 ⊢ β is a constraint that Judith uses quite regularly and unproblematically in reasoning about her heating system. However, during a recent blizzard she was forced to add the premise
(α3) The power is off.
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- Information FlowThe Logic of Distributed Systems, pp. 221 - 234Publisher: Cambridge University PressPrint publication year: 1997