Hans De Meyer

Bio: Hans De Meyer is an academic researcher from Ghent University. The author has contributed to research in topics: Transitive relation & Diagonal. The author has an hindex of 21, co-authored 87 publications receiving 1075 citations.

Exploiting the Lattice of Ideals Representation of a Poset

Abstract: In this paper, we demonstrate how some simple graph counting operations on the ideal lattice representation of a partially ordered set (poset)P allow for the counting of the number of linear extensions of P, for the random generation of a linear extension of P, for the calculation of the rank probabilities for every x∈P, and, finally, for the calculation of the mutual rank probabilities Prob(x>y) for every (x,y)∈P$^2$. We show that all linear extensions can be counted and a first random linear extension can be generated in O(mI(P)m·w(p)) time, while every subsequent random linear extension can be obtained in O(mPm·w(P)) time, where mI(P)m denotes the number of ideals of the poset P and w(P) the width of the poset P. Furthermore, we show that all rank probability distributions can be computed in O(mI(P)m·w(P)) time, while the computation of all mutual rank probabilities requires O(mI(P)m·mPm·w(P)) time, to our knowledge the fastest exact algorithms currently known. It is well known that each of the four problems described above resides in the class of #P-complete counting problems, the counterpart of the NP-complete class for decision problems. Since recent research has indicated that the ideal lattice representation of a poset can be obtained in constant amortized time, the stated time complexity expressions also cover the time needed to construct the ideal lattice representation itself, clearly favouring the use of our approach over the standard ap-proach consisting of the exhaustive enumeration of all linear extensions.

How potential users of music search and retrieval systems describe the semantic quality of music

Abstract: A large-scale study was set up aiming at the clarification of the influence of demographic and musical background on the semantic description of music. Our model for rating high-level music qualities distinguishes between affective-emotive, structural and kinaesthetic descriptors. The focus was on the understanding of the most important attributes of music in view of the development of efficient search and retrieval systems. We emphasized who the users of such systems are and how they describe their favorite music. Particular interest went to inter-subjective similarities among listeners. The results from our study suggest that gender, age, musical expertise, active musicianship, broadness of taste and familiarity with the music have an influence on the semantic description of music. © 2008 Wiley Periodicals, Inc.

An Auditory Model Based Transcriber of Singing Sequences

Abstract: In this paper, a new system for the automatic transcription of singing sequences into a sequence of pitch and duration pairs is presented. Although such a system may have a wider range of applications, it was mainly developed to become the acoustic module of a queryby-humming (QBH) system for retrieving pieces of music from a digitized musical library. The first part of the paper is devoted to the systematic evaluation of a variety of state-of-the art transcription systems. The main result of this evaluation is that there is clearly a need for more accurate systems. Especially the segmentation was experienced as being too error prone ( % segmentation errors). In the second part of the paper, a new auditory model based transcription system is proposed and evaluated. The results of that evaluation are very promising. Segmentation errors vary between 0 and 7 %, dependent on the amount of lyrics that is used by the singer. The paper ends with the description of an experimental study that was issued to demonstrate that the accuracy of the newly proposed transcription system is not very sensitive to the choice of the free parameters, at least as long as they remain in the vicinity of the values one could forecast on the basis of their meaning.

Asymmetric semilinear copulas

Abstract: We complement the recently introduced classes of lower and upper semilinear copulas by two new classes, called vertical and horizontal semilinear copulas, and characterize the corresponding class of diagonals. The new copulas are in essence asymmetric, with maximum asymmetry given by 1/16. The only symmetric members turn out to be also lower and upper semilinear copulas, namely convex sums of II and M.

Transitivity-preserving fuzzification schemes for cardinality-based similarity measures.

Abstract: Abstract A family of fuzzification schemes is proposed that can be used to transform cardinality-based similarity measures for ordinary sets into similarity measures for fuzzy sets in a finite universe. The family is based on rules for fuzzy set cardinality and for the standard operations on fuzzy sets. In particular, the fuzzy set intersections are pointwisely generated by Frank t -norms. The fuzzification schemes are applied to a variety of previously studied rational cardinality-based similarity measures for ordinary sets and it is demonstrated that transitivity is preserved in the fuzzification process.

Aggregation Functions: A Guide for Practitioners

Abstract: Aggregation of information is of primary importance in the construction of knowledge based systems in various domains, ranging from medicine, economics, and engineering to decision-making processes, artificial intelligence, robotics, and machine learning. This book gives a broad introduction into the topic of aggregation functions, and provides a concise account of the properties and the main classes of such functions, including classical means, medians, ordered weighted averaging functions, Choquet and Sugeno integrals, triangular norms, conorms and copulas, uninorms, nullnorms, and symmetric sums. It also presents some state-of-the-art techniques, many graphical illustrations and new interpolatory aggregation functions. A particular attention is paid to identification and construction of aggregation functions from application specific requirements and empirical data. This book provides scientists, IT specialists and system architects with a self-contained easy-to-use guide, as well as examples of computer code and a software package. It will facilitate construction of decision support, expert, recommender, control and many other intelligent systems.

Fuzzy sets and systems

Abstract: The notion of fuzziness as defined in this paper relates to situations in which the source of imprecision is not a random variable or a stochastic process, but rather a class or classes which do not possess sharply defined boundaries, e.g., the “class of bald men,” or the “class of numbers which are much greater than 10,” or the “class of adaptive systems,” etc. A basic concept which makes it possible to treat fuzziness in a quantitative manner is that of a fuzzy set, that is, a class in which there may be grades of membership intermediate between full membership and non-membership. Thus, a fuzzy set is characterized by a membership function which assigns to each object its grade of membership (a number lying between 0 and 1) in the fuzzy set. After a review of some of the relevant properties of fuzzy sets, the notions of a fuzzy system and a fuzzy class of systems are introduced and briefly analyzed. The paper closes with a section dealing with optimization under fuzzy constraints in which an approach to...

Content-Based Music Information Retrieval: Current Directions and Future Challenges

Abstract: The steep rise in music downloading over CD sales has created a major shift in the music industry away from physical media formats and towards online products and services. Music is one of the most popular types of online information and there are now hundreds of music streaming and download services operating on the World-Wide Web. Some of the music collections available are approaching the scale of ten million tracks and this has posed a major challenge for searching, retrieving, and organizing music content. Research efforts in music information retrieval have involved experts from music perception, cognition, musicology, engineering, and computer science engaged in truly interdisciplinary activity that has resulted in many proposed algorithmic and methodological solutions to music search using content-based methods. This paper outlines the problems of content-based music information retrieval and explores the state-of-the-art methods using audio cues (e.g., query by humming, audio fingerprinting, content-based music retrieval) and other cues (e.g., music notation and symbolic representation), and identifies some of the major challenges for the coming years.

Tonal description of music audio signals

Abstract: This doctoral dissertation proposes and evaluates a computational approach for the automatic description of tonal aspects of music from the analysis of polyphonic audio signals. These algorithms focus on the computation of pitch class distributions descriptors, the estimation of the key of a piece, the visualization of the evolution of its tonal center or the measurement of the similarity between two different musical pieces. This dissertation substantially contributes to the field of computational tonal description: a) It provides a multidisciplinary review of tonal induction systems; b) It defines a set of requirements for low-level tonal features; c) It provides a quantitative and modular evaluation of the proposed methods; d) It contributes to bridge the gap between audio and symbolic-oriented methods without the need of a perfect transcription; e) It extents current literature dealing with classical music to other musical genres; f) It shows the usefulness of tonal descriptors for music similarity; g) It provides an optimized method which is used in a real system for music visualization and retrieval, working with over a million of musical pieces.

MPEG-7 Audio and Beyond: Audio Content Indexing and Retrieval

Abstract: List of Acronyms. List of Symbols. 1. Introduction. 1.1 Audio Content Description. 1.2 MPEG-7 Audio Content Description - An Overview. 1.2.1 MPEG-7 Low-Level Descriptors. 1.2.2 MPEG-7 Description Schemes. 1.2.3 MPEG-7 Description Definition Language (DDL). 1.2.4 BiM (Binary Format for MPEG-7). 1.3 Organization of the Book. 2. Low-Level Descriptors. 2.1 Introduction. 2.2 Basic Parameters and Notations. 2.2.1 Time Domain. 2.2.2 Frequency Domain. 2.3 Scalable Series. 2.3.1 Series of Scalars. 2.3.2 Series of Vectors. 2.3.3 Binary Series. 2.4 Basic Descriptors. 2.4.1 Audio Waveform. 2.4.2 Audio Power. 2.5 Basic Spectral Descriptors. 2.5.1 Audio Spectrum Envelope. 2.5.2 Audio Spectrum Centroid. 2.5.3 Audio Spectrum Spread. 2.5.4 Audio Spectrum Flatness. 2.6 Basic Signal Parameters. 2.6.1 Audio Harmonicity. 2.6.2 Audio Fundamental Frequency. 2.7 Timbral Descriptors. 2.7.1 Temporal Timbral: Requirements. 2.7.2 Log Attack Time. 2.7.3 Temporal Centroid. 2.7.4 Spectral Timbral: Requirements. 2.7.5 Harmonic Spectral Centroid. 2.7.6 Harmonic Spectral Deviation. 2.7.7 Harmonic Spectral Spread. 2.7.8 Harmonic Spectral Variation. 2.7.9 Spectral Centroid. 2.8 Spectral Basis Representations. 2.9 Silence Segment. 2.10 Beyond the Scope of MPEG-7. 2.10.1 Other Low-Level Descriptors. 2.10.2 Mel-Frequency Cepstrum Coefficients. References. 3. Sound Classification and Similarity. 3.1 Introduction. 3.2 Dimensionality Reduction. 3.2.1 Singular Value Decomposition (SVD). 3.2.2 Principal Component Analysis (PCA). 3.2.3 Independent Component Analysis (ICA). 3.2.4 Non-Negative Factorization (NMF). 3.3 Classification Methods. 3.3.1 Gaussian Mixture Model (GMM). 3.3.2 Hidden Markov Model (HMM). 3.3.3 Neural Network (NN). 3.3.4 Support Vector Machine (SVM). 3.4 MPEG-7 Sound Classification. 3.4.1 MPEG-7 Audio Spectrum Projection (ASP) Feature Extraction. 3.4.2 Training Hidden Markov Models (HMMs). 3.4.3 Classification of Sounds. 3.5 Comparison of MPEG-7 Audio Spectrum Projection vs. MFCC Features. 3.6 Indexing and Similarity. 3.6.1 Audio Retrieval Using Histogram Sum of Squared Differences. 3.7 Simulation Results and Discussion. 3.7.1 Plots of MPEG-7 Audio Descriptors. 3.7.2 Parameter Selection. 3.7.3 Results for Distinguishing Between Speech, Music and Environmental Sound. 3.7.4 Results of Sound Classification Using Three Audio Taxonomy Methods. 3.7.5 Results for Speaker Recognition. 3.7.6 Results of Musical Instrument Classification. 3.7.7 Audio Retrieval Results. 3.8 Conclusions. References. 4. Spoken Content. 4.1 Introduction. 4.2 Automatic Speech Recognition. 4.2.1 Basic Principles. 4.2.2 Types of Speech Recognition Systems. 4.2.3 Recognition Results. 4.3 MPEG-7 SpokenContent Description. 4.3.1 General Structure. 4.3.2 SpokenContentHeader. 4.3.3 SpokenContentLattice. 4.4 Application: Spoken Document Retrieval. 4.4.1 Basic Principles of IR and SDR. 4.4.2 Vector Space Models. 4.4.3 Word-Based SDR. 4.4.4 Sub-Word-Based Vector Space Models. 4.4.5 Sub-Word String Matching. 4.4.6 Combining Word and Sub-Word Indexing. 4.5 Conclusions. 4.5.1 MPEG-7 Interoperability. 4.5.2 MPEG-7 Flexibility. 4.5.3 Perspectives. References. 5. Music Description Tools. 5.1 Timbre. 5.1.1 Introduction. 5.1.2 InstrumentTimbre. 5.1.3 HarmonicInstrumentTimbre. 5.1.4 PercussiveInstrumentTimbre. 5.1.5 Distance Measures. 5.2 Melody. 5.2.1 Melody. 5.2.2 Meter. 5.2.3 Scale. 5.2.4 Key. 5.2.5 MelodyContour. 5.2.6 MelodySequence. 5.3 Tempo. 5.3.1 AudioTempo. 5.3.2 AudioBPM. 5.4 Application Example: Query-by-Humming. 5.4.1 Monophonic Melody Transcription. 5.4.2 Polyphonic Melody Transcription. 5.4.3 Comparison of Melody Contours. References. 6. Fingerprinting and Audio Signal Quality. 6.1 Introduction. 6.2 Audio Signature. 6.2.1 Generalities on Audio Fingerprinting. 6.2.2 Fingerprint Extraction. 6.2.3 Distance and Searching Methods. 6.2.4 MPEG-7-Standardized AudioSignature. 6.3 Audio Signal Quality. 6.3.1 AudioSignalQuality Description Scheme. 6.3.2 BroadcastReady. 6.3.3 IsOriginalMono. 6.3.4 BackgroundNoiseLevel. 6.3.5 CrossChannelCorrelation. 6.3.6 RelativeDelay. 6.3.7 Balance. 6.3.8 DcOffset. 6.3.9 Bandwidth. 6.3.10 TransmissionTechnology. 6.3.11 ErrorEvent and ErrorEventList. References. 7. Application. 7.1 Introduction. 7.2 Automatic Audio Segmentation. 7.2.1 Feature Extraction. 7.2.2 Segmentation. 7.2.3 Metric-Based Segmentation. 7.2.4 Model-Selection-Based Segmentation. 7.2.5 Hybrid Segmentation. 7.2.6 Hybrid Segmentation Using MPEG-7 ASP. 7.2.7 Segmentation Results. 7.3 Sound Indexing and Browsing of Home Video Using Spoken Annotations. 7.3.1 A Simple Experimental System. 7.3.2 Retrieval Results. 7.4 Highlights Extraction for Sport Programmes Using Audio Event Detection. 7.4.1 Goal Event Segment Selection. 7.4.2 System Results. 7.5 A Spoken Document Retrieval System for Digital Photo Albums. References. Index.