OpenMath Content Dictionary: directives1

Canonical URL:
http://www.riaca.win.tue.nl/cds/directives/directives1.ocd
CD Base:
http://www.openmath.org/cd
CD File:
directives1.ocd
CD as XML Encoded OpenMath:
directives1.omcd
Defines:
decide, disprove, evaluate, evaluate_to_type, explore, find, look_up, prove, prove_in_theory, response
Date:
2004-06-01
Version:
1 (Revision 3)
Review Date:
2006-06-01
Status:
experimental

The primal objective of OpenMath objects is to represent mathematical expressions. In this Content Dictionary another objective is addressed, namely to express an action related to a mathematical expression. Such a request for an action is generally referred to as a query. The specific queries are called directives. In this CD we define some. An entity (software) carrying out the query is referred to as a service. The service might return an OpenMath object. To formalize this object, we also introduce the symbol response in this CD.

amc 2004-03-18: added the directive explore. amc 2004-03-24: removed redundancies.


evaluate

Description:

This symbol is a function with one argument, which should be a mathematical expression. When applied to a mathematical expression, it asks for an evaluation or simplification of the expression. The evaluation or simplification to be carried out by a service is a simpler mathematical expression (in some definition of complexity of objects) which is equal to the argument.

Example:
The value of sin(Pi) is zero. The expression below asks for sin(Pi) to be evaluated, and so a service receiving the object is supposed to return zero.
evaluate ( sin ( π ) )
Signatures:
sts


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evaluate_to_type

Description:

This symbol is a function with two arguments, which should be a mathematical expression and a type. When applied to a mathematical expression E and a type T, it asks for an evaluation or simplification of E to a mathematical expression of type T.

Example:
The value of (7*6)/2 is a natural number. The expression below asks for this integer.
evaluate ( 7 × 6 2 , N )
Commented Mathematical property (CMP):
The type of the responded object should be equal to the specification, that is the second argument of the evaluate_to_type.
Formal Mathematical property (FMP):
response ( evaluate_to_type ( x , T ) )
Signatures:
sts


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look_up

Description:

This symbol is a function with one argument, which should be a mathematical expression. When applied to a mathematical expression, it asks for mathematical expressions related to the argument. If the argument is a single OpenMath symbol, the service might respond by the list of all properties in the CD containing the argument. Alternatively, the service can provide a list of CDs which use the CD in which the argument occurs.

Another service might return all documents in which the symbol occurs.

If the argument is a more complicated object, the same services could be called for, but then with all OpenMath symbols occurring in the argument instead of the single one.

Example:
Looking up sin is expressed as follows:
look_up ( sin )
Signatures:
sts


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response

Description:

This symbol is a function of one argument, which should be a query. When applied to a query, it refers to the response a service might give. It will mainly be used in this CD to express formal mathematical properties of queries.

Signatures:
sts


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prove

Description:

This symbol is a function with one argument, which should be a clause. When applied to a clause C, it asks for a proof of C.

Signatures:
sts


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disprove

Description:

This symbol is a function with one argument, which should be a clause. When applied to a clause C, it asks for a proof of that C does not hold.

Commented Mathematical property (CMP):
Asking to disprove C amounts to asking for a proof that C does not hold. (In other words, this symbol is completely redundant, even in multi-valued logic.***)
Formal Mathematical property (FMP):
disprove ( C ) = prove ( ¬ C )
Signatures:
sts


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prove_in_theory

Description:

This symbol is a function with two arguments, the first of which should be a clause and the second of which should be a symbol indicating a logic theory. When applied to arguments C, T, it asks for a proof of C in theory T.

Signatures:
sts


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find

Description:

This symbol is a binder, whose body should be a clause. When bound to a variable (or list of variables) x with body P(x), it asks for a mathematical expression A such that P(A) holds.

Example:
Searching for a real number x such that sin(x) = 0
find x . x R sin ( x ) = 0
is to be compared to asking for an inverse of x:
evaluate_to_type ( ( sin -1 ) ( 0 ) , R )
Commented Mathematical property (CMP):
The body of argument with the binder x replaced by the response should be a true statement.
Formal Mathematical property (FMP):
P ( response ( find x . P ) )
Signatures:
sts


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decide

Description:

This symbol is a function with one argument, which should be a clause. When applied to a clause, it asks whether the clause holds.

Example:
The question if sin(Pi) is equal to zero can be phrased as follows.
decide ( sin ( π ) = 0 )
Commented Mathematical property (CMP):
The response to the decide query is logically equivalent to the truth of the argument.
Formal Mathematical property (FMP):
response ( decide ( P ) ) P
Signatures:
sts


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explore

Description:

This symbol is a unary function whose argument should be a mathematical assertion. When applied to an assertion A, it asks for conditions under which the assertion holds.

Example:
Given the Pappos configuration P, the Pappos thesis T asserts that three points of the configuration are collinear. A conceivable answer to the explore directive with the assertion that in configuration P the thesis T holds, is a nondegeneracy condition that makes the assertion valid.
Commented Mathematical property (CMP):
A response R should satisfy the requirement that R implies the assertion.
Formal Mathematical property (FMP):
response ( explore ( A ) ) A
Signatures:
sts


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