Method for predicting keystroke characters on single pointer keyboards and apparatus therefore
First Claim
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1. A method for predicting keystrokes on a keyboard, comprising the steps of:
- constructing a model from a training corpus including symbol sequences, wherein symbols in the model are stored in a reverse order of occurrence of the symbols;
predicting a set of symbols by traversing the model from a root node backwards once, through the reverse order of occurrence of the symbols, each symbol of the set continuing a particular symbol sequence using variable-length subsequences of the particular symbol sequence, a particular length of the subsequences chosen to maximize a probability that the predicting is correct;
highlighting keys on the keyboard, the highlighted keys corresponding to selected symbols of the predicted set of symbols.
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Abstract
Keystrokes on a keyboard are predicted by constructing a model from a training corpus. The training corpus includes symbol sequences. The model predicts a set of symbols, where each symbol of the set continues a particular symbol sequence using variable-length subsequences of the particular symbol sequence. A particular length is chosen to maximize a probability that the predicting is correct. Keys on the keyboard are highlighted. The highlighted keys correspond to selected symbols in the set of symbols.
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Citations
11 Claims
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1. A method for predicting keystrokes on a keyboard, comprising the steps of:
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constructing a model from a training corpus including symbol sequences, wherein symbols in the model are stored in a reverse order of occurrence of the symbols;
predicting a set of symbols by traversing the model from a root node backwards once, through the reverse order of occurrence of the symbols, each symbol of the set continuing a particular symbol sequence using variable-length subsequences of the particular symbol sequence, a particular length of the subsequences chosen to maximize a probability that the predicting is correct;
highlighting keys on the keyboard, the highlighted keys corresponding to selected symbols of the predicted set of symbols. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
assigning a probability of 1.0 to the root node of the model, the root node having a default “
null”
symbol;
constructing a first layer of nodes connected to the root node, each node of the first layer representing a unique symbol of the training corpus and a probability of the frequency that the symbol appears in the training corpus;
reexamining the training corpus according to the model to construct a next layer, each node in the next layer representing a particular symbol preceding a connected node in the first layer and a probability of the frequency that the particular symbol precedes the connected node; and
repeating the reexamination of the training corpus and the constructing of the next layer until a termination condition is reached.
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5. The method of claim 4 further comprising the step of:
pruning the particular node in the model when the particular node has a probability less than a predetermined threshold.
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6. The method of claims 1 wherein the model is a decision tree.
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7. The method of claims 1 wherein the model is a decision tree, and wherein redundant nodes are pruned.
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8. The method of claim 6 wherein each node of the decision tree stores a current symbol and an ordered set of predicted symbols.
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9. The method of claim 6 wherein the decision tree is derived from a variable memory length Markov model.
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10. A predictive keyboard, comprising:
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a memory storing a model constructed from a training corpus including symbol sequences, wherein symbols in the model are stored in a reverse order of occurrence of the symbols, the model predicting a set of symbols by traversing the model backwards once, from a root node through the reverse order of occurrence of the symbols, each symbol of the set continuing a particular symbol sequence using variable-length subsequences of the particular symbol sequence, a particular length chosen to maximize a probability that the predicting is correct;
a plurality of keys; and
means for highlighting particular keys, the highlighted keys corresponding to selected symbols of the set of symbols.
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11. A method for predicting keystrokes on a keyboard from a sequence of typed symbols, comprising the steps of:
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constructing a decision tree where a root node has a set of most frequently occurring symbols in a training corpus, and each node in each next layer storing an ordered set of symbols that would precede symbols of a node of a previous layer;
traversing the decision tree once to predict probable next symbols to be typed, the searching beginning at the root and proceeding in a reverse order to find a sequence of symbols in the decision tree that matches a subset of the sequence of the typed symbols; and
highlighting keys on the keyboard, the highlighted keys corresponding to the probable next symbols.
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Specification