In this paper, we describe a computational approach for authorship attribution of literary texts in a multilingual environment. First, we define a set of syntactical features at text structural levels by considering the internal grammatical structure of sentences. The main idea is to extract syntactic functions from every word necessary to make up a sentence, such as subject and predicate. Such elements denote a writing pattern, tracking a stylometric profile for each author. Second, we gather literary texts in five languages: Portuguese, Spanish, French, German, and English. We analyze distinct scenarios through a series of experiments, taking into account writer-dependent and writer-independent approaches while using authorship verifica- tion and identification strategies. Furthermore, we evaluate the model behavior when the amount of information in each sample is varied and the impact of the reference samples. We use a support vector machine classifier in this process.

This paper presents a syntactic approach for the authorship attribution to literary texts. To this end, syntactic features were used in verification and identification approaches. We used also, a classification method based on dissimilarity that has been successfully applied in cases of authorship attribution. In addition, to evaluating two models, the writer-dependent model and writer-independent, we tested approaches based on polytomy and dichotomy. We also tested the impact of the redundancy, by varying the number of references for verification and identification, for short and long texts. In order to meet these goals, we conducted experiments with four different databases, which are journalistic and literary texts in Portuguese and English languages. Through a series of experiments, we showed that the proposed approach was able to surpass the results reported in the literature, in both languages. In our experiments the proposed approach achieved results higher than 90% in both languages for verification and above 75% for the identification.

Current paper describes the use of a feature selection technique to reduce the number of features while the goodness set is selected on a framework for forensic handwriting identification. A sequential forward search and an evaluation criterion based on dependency were used to obtain a goodness subset (GS) to improve the identification rate. The accuracy of the system applied to 100 different writers and taking account all features (N = 81) is 58%, whereas the accuracy based on goodness subset (GS) is 80% applied to the same number of writers. The validation of results was verified initially against all the features and later against some empirically set of features. Results are comparable to others in the literature on graphometric features.

In this paper we present an alternative strategy to define zoning for handwriting recognition, which is based on nonsymmetrical perceptual zoning. The idea is to extract some knowledge from the confusion matrices in order to make the zoning process less empirical. The feature set considered in this work is based on concavities/convexities deficiencies, which are obtained by labeling the background pixels of the input image. To better assess the nonsymmetrical zoning we carried out experiments using four different zonings strategies. Experiments show that the nonsymmetrical zoning could be considered as a tool to build more reliable handwriting recognition systems.

The study investigates the perceptual feature similarity between different lexicons based on visual perception of the words and their representation through an observation sequence. We confirm that it is possible to use databases, which are similar in terms of morphological/perceptual features to improve the recognition performance. In this work, we demonstrated through experimentation, that it is possible to improve the recognition rate of handwritten Portuguese words by adding samples of French words in the training set. Experimental results show the efficiency of this strategy reducing the error rate.

In this paper a word recognition and verification scheme based on HMMs is presented. However, the main contribution of the current work lies in the validation of such a strategy. In order to perform this task, we carried out some experiments on word recognition using a legal amount database and then we compared the results reached with other study which makes use of the same database. The experiments demonstrate the efficiency of the strategy we developed for word recognition and verification.

... learning is proposed. It makes use of a multiobjective genetic algorithm where the minimization of the number of features and a validity index that measures the quality of clusters have been used to guide the search towards the more discriminant features and the best number of clusters. The proposed strategy is evaluated using two synthetic data sets and then it is applied to handwritten month word recognition. Comprehensive experiments demonstrate the feasibility and efficiency of the proposed methodology.

Feature selection for ensembles has shown to be an effective strategy for ensemble creation. In this paper we present an ensemble feature selection approach based on a hierarchical multi-objective genetic algorithm. The first level performs feature selection in order to generate a set of good classifiers while the second one combines them to provide a set of powerful ensembles. The proposed method is evaluated in the context of handwritten digit recognition, using three different feature sets and neural networks (MLP) as classifiers. Experiments conducted on NIST SD19 demonstrated the effectiveness of the proposed strategy.

In this paper a methodology for feature selection for the handwritten digit string recognition is proposed. Its novelty lies in the use of a multiobjective genetic algorithm where sensitivity analysis and neural network are employed to allow the use of a representative database to evaluate fitness and the use of a validation database to identify the subsets of selected features that provide a good generalization. Some advantages of this approach include the ability to accommodate multiple criteria such as number of features and accuracy of the classifier, as well as the capacity to deal with huge databases in order to adequately represent the pattern recognition problem. Comprehensive experiments on the NIST SD19 demonstrate the feasibility of the proposed methodology.

A modular system to recognize handwritten numerical strings is proposed. It uses a segmentation-based recognition approach and a recognition and verification strategy. The approach combines the outputs from different levels such as segmentation, recognition, and postprocessing in a probabilistic model. A new verification scheme which contains two verifiers to deal with the problems of oversegmentation and undersegmentation is presented. A new feature set is also introduced to feed the oversegmentation verifier. A postprocessor based on a deterministic automaton is used and the global decision module makes an accept/reject decision. Finally, experimental results on two databases are presented: numerical amounts on Brazilian bank checks and NIST SD19. The latter aims at validating the concept of modular system and showing the robustness of the system using a well-known database.

The authors propose a handwritten numeral string recognition method composed of two HMM-based stages. The first stage uses an implicit segmentation strategy based on string contextual information to provide multiple segmentation-recognition paths. These paths are verified and re-ranked by using a verification stage based on a digit classifier. It allows the use of two sets of features and numeral models: one taking into account both segmentation and recognition aspects in an implicit segmentation based strategy, and another considering just recognition aspects of isolated digits. The two system stages are shown to be complementary in the sense that the verification stage is shown to be a promising idea to deal with the loss in terms of recognition performance brought about by the necessary tradeoff between segmentation and recognition carried out in the first system stage.

The paper presents the application of the Mutual Information criterion (T.M. Cover and J.A. Thomas, 1991) to validate feature sets extracted from handwritten words in Brazilian legal amounts. The lexicon includes a subset of short words without ascenders/descenders and subsets of words with the same prefix or suffix. These particularities of the Brazilian lexicon show that it is necessary to improve the perpetual feature set with complementary geometric features, and also modeling the prefix and suffix of the words. Finally, the experiments show the viability of our approach.

The problem of signature verification is in theory a pattern recognition task used to discriminate two classes, original and forgery signatures. Even after many efforts in order to develop new verification techniques for static signature verification, the influence of the forgery types has not been extensively studied. This paper reports the contribution to signature verification considering different forgery types in an HMM framework. The experiments have shown that the error rates of the simple and random forgery signatures are very closed. This reflects the real applications in which the simple forgeries represent the principal fraudulent case. In addition, the experiments show promising results in skilled forgery verification by using simple static and pseudodynamic features.

This paper describes an off-line system under development to process unconstrained handwritten dates on Brazilian bank cheques in an omni-writer context. We show here some improvements on our previous work on isolated month word recognition using hidden Markov models (HMM). After preprocessing, a word image is explicitly segmented into characters or pseudo-characters and represented by two feature sequences of equal length, which are combined using HMM. The word models are generated from the concatenation of appropriate character models. In addition to the small date database, we also make use of the legal amount database to increase the frequency of characters in the training and the validation sets. Although this study deals with a limited lexicon, the many similarities among the word classes can affect the performance of the recognition. Experiments show an increase in the average recognition rate from 84% to 91%. Finally, we present our perspectives of future work.

The paper presents a modular system to recognize numerical amounts on Brazilian bank cheques. The system uses a segmentation-based recognition approach and the recognition function is based on a recognition and verification strategy. Our approach consists of combining the outputs from different levels such as segmentation, recognition and post-processing in a probabilistic model. A new feature set is introduced to the verifier module in order to detect segmentation effects such as over-segmentation and under-segmentation. Finally, we present experimental results on two databases: numerical amounts and NIST SD19. The latter aims at validating the concept of modular system and showing the robustness of the system over a well-known database.

An approach to correct the baseline handwritten word skew in the image of bank check dates is presented. The main goal of such an approach is to reduce the use of empirical thresholds. The weighted least squares approach is used on the pseudo-convex hull obtained from the mathematical morphology.

This paper presents an Off-line Signature Verification System for identifying random forgeries aimed at banking application. The cognitive information learning process in the proposed system is inspired by some characteristics of human learning. Four features distinguish the proposed system from those proposed thus far. First, the verification task is accomplished without a priori knowledge of the class of random forgeries. Second, no explicit modeling or making geometrical measurements are used to represent the signature. Third, the decision of the system is made throughout the use of two-stage verification process by which a global and/or local analysis are performed on the unknown signature. The global analysis is concerned with the overall shape of the unknown signature, whereas, the local analysis is concerned with the local features composing the unknown signature. Fourth, these analysis are performed at the boundary or within a predefined search region called the identity grid designed for each writer in the system. The proposed system is evaluated with a data base of 800 signatures.

The discrimination between breast carcinoma cell nuclei and artifacts from cytological images is one key element for achieving analysis of cell characteristics, which is useful for tumour prognosis. In this paper the identification of cell nuclei is carried out by means of a Bayesian classifier integrating reject options and its use for classes whose distributions have unequal covariance matrices is analysed. This analysis is more general than the one introduced earlier by Dubuisson and Masson (1992), and shows that there are other consequences from using rejects to be discussed. We make a comparison between two Bayesian classifiers and the experimental results are presented.

This work investigates the use of a fuzzy ARTMAP neural network for detecting cancerous cells, based on the one-class problem approach. This approach is inspired by the way human beings perform pattern recognition. We all know that children and adults alike are capable of detecting patterns belonging to a certain class, by learning the features of these patterns only. Moreover, a child or an adult is capable of detecting an unknown pattern belonging to another class without an a priori knowledge of the features in these patterns. Based on this approach, a fuzzy ARTMAPs-based system is developed for detecting cancerous cells by training the fuzzy ARTMAPs with the features belonging to the class of cancerous cells only. This is different from the two-class problem approach which requires that the classifier must be trained with features from the class of cancerous cells and the class of noncancerous cells. Experimental analysis were conducted using a set of 542 patterns taken from a sample of breast cancer. Training was performed with 383 cancerous cells. System performance was evaluated using 54 cancerous cells and 159 noncancerous cells. Evaluation results show 98% correct identification of cancerous cells and 95% correct identification of noncancerous cells.

This work proposes a new approach to signature verification. It is inspired by the human learning and the approach adopted by the expert examiner of signatures, in which an a priori knowledge of the class of forgeries is not required in order to perform the verification task. Based on this approach, we present a Fuzzy ARTMAP based system for the elimination of random forgeries. Compared to the conventional systems proposed thus far, the presented system is trained with genuine signatures only. Six experiments have been performed on a data base of 200 signatures taken from five writers (40 signatures/writer). Evaluation of the system was measured using different numbers of training signatures.