Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-06-02
2002-10-15
Metjahic, Safet (Department: 2171)
Data processing: database and file management or data structures
Database design
Data structure types
C712S210000
Reexamination Certificate
active
06466930
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an apparatus and method for processing data.
BACKGROUND OF THE INVENTION
Data processing frequently involves the evaluation of expressions, formed by combining operand values and operators according to defined rules of syntax. For example, the expression
(A and B) or (not C)
involves operand values A, B and C and logical operators “and”, “or” and “not”. The evaluation of an expression returns a result value, which in the above example will be either “true” or “false”.
Conventionally, each operand value represents the value of some attribute at a particular point in time, and the result represents the result of the evaluation at that point in time. For example, a value may be a numeric value representing a person's current salary, or may be a string value, representing the person's current address. However, conventional expression evaluation mechanisms are not well adapted to handle situations where the operand values change over time.
The object of the present invention is to provide a novel apparatus and method for evaluating expressions involving values which change over time.
SUMMARY OF THE INVENTION
According to the invention, a data processing method comprises:
(a) providing a plurality of expressions, each expression including a number of temporally-scoped operands; and
(b) evaluating the expressions to produce temporally-scoped results;
(c) wherein each of the temporally-scoped operands and results comprises a sequence of one or more value instances, each value instance including a data item, a start time, and an end time, the start time and end time defining a time span in which the data item is valid.
The invention also includes data processing apparatus for performing this method.
REFERENCES:
patent: 5239663 (1993-08-01), Faudemay et al.
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patent: 5485612 (1996-01-01), Ota et al.
patent: 5832224 (1998-11-01), Fehskens et al.
patent: 5924103 (1999-07-01), Ahmed et al.
patent: 6205441 (2001-03-01), Al-omari et al.
patent: 6247115 (2001-06-01), Janik et al.
Chen Te Yu
International Computers Limited
Lee Mann Smith McWilliams Sweeney & Ohlson
Metjahic Safet
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