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C00002 00002	mud[s86,jmc]		All about mud for the common sense database
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mud[s86,jmc]		All about mud for the common sense database

	It may be worthwhile to write axioms for common phenomena.  These
axioms will be restricted to the phenomenon in question and will require
more general axioms about the common sense world in order to be used.  The
form of the specific knowledge may suggest the form the general knowledge
should take.

	We should try two kinds of phenomena.  One kind is where most
humans have considerable experience, and the other is one in which
many humans have no experience but can learn about the phenomenon
from a book well enough to succeed.

1. To escape from a sunken submarine, wait till the pressure of the trapped
air in your punctured compartment reaches the pressure of the water
outside.  Then leave the submarine and swim to the surface exhaling
as the water pressure reduces.  This will work for depths up to 300 feet.
You will avoid the bends if the pressure equalizes in a few minutes.

This is perhaps too imperative for present purposes.

2. Mud is a mixture of dirt and water.  The kind of mud depends on the
kind of dirt and on how much water is mixed with it.  The less water
there is in the mud the bigger a piece of mud can be without slumping.
Mud is penetrable by objects including human hands and feet.  If you
walk in mud you will sink in to the bottom if the mud is shallow or
up to you neck if the mud is deep enough.
The color of mud is usually brown, but some kinds are gray.
Mud will dry out unless it is covered with water.

This needs rough quantitative information.  How big are the quantities
of mud encountered?  How long does it take mud to slump or dry out?

Clearly mud satisfies the general properties of materials including
the fact that objects may be made of it.


Material objects

	Material objects have location and extent in situations.  They
may be created and destroyed, moved and modified.  There are approximate
conventions about when a modification is considered to destroy the
object.  The matter is conserved.