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OpenMath Content Dictionary: plangeo1

Canonical URL:
http://www.win.tue.nl/~amc/oz/om/cds/plangeo1.ocd
CD Base:
http://www.openmath.org/cd
CD File:
plangeo1.ocd
CD as XML Encoded OpenMath:
plangeo1.omcd
Defines:
assertion, configuration, incident, line, point, type, are_on_line
Date:
2004-06-01
Version:
0 (Revision 5)
Review Date:
2006-06-01
Status:
experimental

This CD defines symbols for planar Euclidean geometry.


point

Description:

The symbol is used to indicate a point of planar Euclidean geometry by a variable. The point may (but need not) be subject to constraints. The symbol takes the variable as the first argument and the constraints as further arguments.

Example:
Given two lines l and m, a point A on l and m is defined by:
point ( A , incident ( A , l ) , incident ( A , m ) )
Signatures:
sts


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line

Description:

The symbol is used to indicate a line of planar Euclidean geometry by a variable. The line may (but need not) be subject to constraints. The symbol takes the variable as the first argument and the constraints as further arguments.

Example:
Given points A and B, a line l through A and B is defined by:
line ( l , incident ( A , l ) , incident ( B , l ) )
Signatures:
sts


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incident

Description:

The symbol represents the logical incidence function which is a binary function taking arguments representing geometric objects like points and lines and returning a boolean value. It is true if and only if the first argument is incident to the second.

Example:
That a point A is incident to a line l is given by:
incident ( A , l )
Signatures:
sts


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configuration

Description:

The symbol represents a configuration in Euclidean planar geometry consisting of a sequence of geometric objects like points, lines, etc, but also of other configurations.

Example:
The configuration of a point A and a line l incident to A is defined by:
configuration ( point ( A ) , line ( l , incident ( A , l ) ) )
Example:
The prevous configuration of a point A and a line l incident with A can be extended by adding a second point B incident with l:
configuration ( configuration ( point ( A ) , line ( l , incident ( A , l ) ) ) , point ( B , incident ( B , l ) ) )
Example:
We describe a triangle on the distinct points A, B, C and lines a, b, c:
configuration ( point ( A ) , point ( B , ¬ ( A = B ) ) , line ( c , incident ( c , A ) , incident ( c , B ) ) , point ( C , ¬ incident ( C , c ) ) , line ( a , incident ( a , B ) , incident ( a , C ) ) , line ( b , incident ( b , A ) , incident ( b , C ) ) )
Signatures:
sts


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type

Description:

The symbol represents the type of the basic geometric objects: points, lines, configuration.

Commented Mathematical property (CMP):
If A and B are objects of the same type, then they are not incident.
Formal Mathematical property (FMP):
type ( A ) = type ( B ) ¬ incident ( A , B )
Signatures:
sts


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assertion

Description:

The symbol is a constructor with two arguments. Its first argument should be a configuration, its second argument a statement about the configuration, called thesis. When applied to a configuration C and a thesis T, the OpenMath object assertion(C,T) expresses the assertion that T holds in C.

Example:
The assertion that two distinct lines meet in only one point can be expressed as follows using the assertion symbol.
assertion ( configuration ( point ( A ) , point ( B ) , line ( l , incident ( A , l ) , incident ( B , l ) ) , line ( m , incident ( A , m ) , incident ( B , m ) , ¬ ( l = m ) ) , A = B ) )
Signatures:
sts


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are_on_line

Description:

The statement that a set of points is collinear.

Example:
This example states that A, B, C, and D are collinear.
are_on_line ( A , B , C , D )
Signatures:
sts


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