Method and apparatus for processing graphically input equations
First Claim
1. A method for processing handwritten equations on a computer system comprising the steps of:
- receiving an input pattern comprising an equation which was derived from user handwritten strokes on a graphical user input device;
parsing said input pattern utilizing a defined constrained attribute grammar to determine if said input pattern defines a valid pattern within said constrained attribute grammar, said valid pattern including a set of subpatterns satisfying constraints of production rules included in said constrained attribute grammar, said constraints being used by said parsing step to establish correspondence between said subpatterns and said production rules, said constraints including keywords to be identified within said subpatterns;
providing a parsed tree from said step of parsing said input pattern when said input pattern is determined to be a valid pattern in said parsing step;
deriving and displaying said equation and a result of said equation utilizing said parsed tree by executing an operator at nodes of said parsed tree using operands included in said parsed tree, wherein said receiving, parsing, providing, and deriving steps are performed on said computer system;
detecting an edit made to said displayed equation having said result; and
editing said parsed tree associated with said equation in response to said edit made to said displayed equation and without changing a structure of said parsed tree when said edit changes only a value or an operator of said equation.
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Abstract
A method for processing equations in a graphical computer system characterized by the steps of: receiving at least one unit comprising an equation which was derived from a graphical user input device; parsing the units into a parsed tree utilizing a constrained attribute grammar; and deriving a result of the equation utilizing the parsed tree. Preferably, the graphical user input device is a table or the screen of a pen-based computer system, where stroke units derived from strokes made by a stylus on the screen are passed to at least one recognition domain. The process preferably also includes the steps of: receiving at least one stroke unit comprising an edit to an equation on the screen; determining whether the edit changes the structure of the parsed tree of the equation; and editing the parsed tree if the edit does not change the structure of the parsed tree. A system for processing equations is characterized by: a digital processor; a screen assembly coupled to the digital processor for displaying images in response to signals provided by the digital processor and for transmitting signals to the digital processor in response to stroke made on the screen assembly with a stylus; an equation recognizer responsive to the stroke signals and operative to detect valid equations formed on the screen; an equation solver operative to produce a result for valid equations; and a mechanism for displaying the result on the screen assembly proximate to the equation.
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Citations
24 Claims
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1. A method for processing handwritten equations on a computer system comprising the steps of:
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receiving an input pattern comprising an equation which was derived from user handwritten strokes on a graphical user input device; parsing said input pattern utilizing a defined constrained attribute grammar to determine if said input pattern defines a valid pattern within said constrained attribute grammar, said valid pattern including a set of subpatterns satisfying constraints of production rules included in said constrained attribute grammar, said constraints being used by said parsing step to establish correspondence between said subpatterns and said production rules, said constraints including keywords to be identified within said subpatterns; providing a parsed tree from said step of parsing said input pattern when said input pattern is determined to be a valid pattern in said parsing step; deriving and displaying said equation and a result of said equation utilizing said parsed tree by executing an operator at nodes of said parsed tree using operands included in said parsed tree, wherein said receiving, parsing, providing, and deriving steps are performed on said computer system; detecting an edit made to said displayed equation having said result; and editing said parsed tree associated with said equation in response to said edit made to said displayed equation and without changing a structure of said parsed tree when said edit changes only a value or an operator of said equation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for processing handwritten equations comprising:
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digital processing means; screen means coupled to said digital processing means, said screen means being operative to display images in response to signals from said digital processing means and to transmit stroke signals to said digital processing means in response to the movement of a stylus means across said screen means; equation recognition means responsive to said stroke signals and operative to detect valid equations formed on said screen means, said equation recognition means including; means for parsing said equation to form a parsed tree, said means for parsing utilizing a constrained attribute grammar including a set of production rules, wherein said stroke signals are input to said means for parsing as a pattern including a set of subpatterns, and means for detecting whether a valid parsed tree has been formed by checking when said set of subpatterns can be rewritten as a start symbol according to said production rules and constraints included within said production rules, said constraints including keywords to be identified in said subpatterns; equation solving means operative to provide a result for said valid equations from said valid parsed tree; means for displaying said equation and said result on said screen proximate to said equation; and editing means for detecting an edit to said displayed equation and for editing said parsed tree in response to said edit to said displayed equation and without changing a structure of said parsed tree. - View Dependent Claims (14, 15, 16)
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17. A computer system for processing handwritten equations comprising:
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a) means for receiving an input pattern comprising an equation which was derived from user handwritten strokes on an input tablet; b) a parser for parsing said input pattern, said parser including; i) means for recognizing said input pattern as a valid pattern utilizing a defined constrained attribute grammar, said grammar including a set of production rules and a grammar start symbol, wherein said means for recognizing determines when said input pattern is valid by determining when said set of input subpatterns can be rewritten as said start symbol according to said set of production rules, wherein said production rules include a syntactic part, a semantic part, a constraints part, and an action part, said constraints part including spatial constraints that require predetermined spatial relationships be satisfied between said input subpatterns; and ii) means for providing a parsed tree when said means for recognizing recognizes said input pattern as a valid pattern; c) data manipulation means for deriving a result of said equation utilizing said parsed tree by executing an operator at nodes of said parsed tree using operands included in said parsed tree; and d) editing means for detecting an edit to said equation and for editing said parsed tree in response to said edit to said equation and without changing a structure of said parsed tree. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification