Call for Participation: SIMBAD 2011 — Similarity-Based Pattern Analysis and Recognition (Venice)



1st International Workshop on Similarity-Based Pattern Analysis and Recognition

28-30 September, 2011
Venice, Italy

(Deadline for Early Registration: 20 September 2011)


Traditional pattern recognition techniques are intimately linked to
the notion of “feature spaces.” Adopting this view, each object is
described in terms of a vector of numerical attributes and is
therefore mapped to a point in a Euclidean (geometric) vector space so
that the distances between the points reflect the observed
(dis)similarities between the respective objects. This kind of
representation is attractive because geometric spaces offer powerful
analytical as well as computational tools that are simply not
available in other representations. Indeed, classical pattern
recognition methods are tightly related to geometrical concepts and
numerous powerful tools have been developed during the last few
decades, starting from the maximum likelihood method in the 1920’s, to
perceptrons in the 1960’s, to kernel machines in the 1990’s.

However, the geometric approach suffers from a major intrinsic
limitation, which concerns the representational power of vectorial,
feature-based descriptions. In fact, there are numerous application
domains where either it is not possible to find satisfactory features
or they are inefficient for learning purposes. This modeling
difficulty typically occurs in cases when experts cannot define
features in a straightforward way (e.g., protein descriptors vs.
alignments), when data are high dimensional (e.g., images), when
features consist of both numerical and categorical variables (e.g.,
person data, like weight, sex, eye color, etc.), and in the presence
of missing or inhomogeneous data. But, probably, this situation arises
most commonly when objects are described in terms of structural
properties, such as parts and relations between parts, as is the case
in shape recognition.

In the last few years, interest around purely similarity-based
techniques has grown considerably. For example, within the supervised
learning paradigm (where expert-labeled training data is assumed to be
available) the well-established kernel-based methods shift the focus
from the choice of an appropriate set of features to the choice of a
suitable kernel, which is related to object similarities. However,
this shift of focus is only partial, as the classical interpretation
of the notion of a kernel is that it provides an implicit
transformation of the feature space rather than a purely
similarity-based representation. Similarly, in the unsupervised
domain, there has been an increasing interest around pairwise or even
multiway algorithms, such as spectral and graph-theoretic clustering
methods, which avoid the use of features altogether.

By departing from vector-space representations one is confronted with
the challenging problem of dealing with (dis)similarities that do not
necessarily possess the Euclidean behavior or not even obey the
requirements of a metric. The lack of the Euclidean and/or metric
properties undermines the very foundations of traditional pattern
recognition theories and algorithms, and poses totally new
theoretical/computational questions and challenges.

The workshop will mark the end of the EU FP7 Projects SIMBAD
(, which was devoted precisely to these themes,
and is a follow-up of the ICML 2010 Workshop on “Learning in
non-(geo)metric spaces” ( Its
aim is to consolidate research efforts in this area, and to provide an
informal discussion forum for researchers and practitioners interested
in this important yet diverse subject. We will be covering a wide
range of problems and perspectives, from supervised to unsupervised
learning, from generative to discriminative models, and from
theoretical issues to real-world practical applications.


The workshop will feature contributed talks and posters as well as
invited presentations by:

– Ulrike Hahn, Cardiff University, UK
– Marco Gori, University of Siena, Italy
– John Shawe-Taylor, University College London, UK

A detailed program can be found at:

We feel that the more informal the better, and we would like to
solicit open and lively discussions and exchange of ideas from
researchers with different backgrounds and perspectives. Plenty of
time will be allocated to questions, discussions, and breaks.

The workshop is supported by PASCAL 2 and IAPR.


Program Chairs
Marcello Pelillo, University of Venice, Italy
Edwin Hancock, University of York, UK

Steering Committee
Joachim Buhmann, ETH Zurich, Switzerland
Robert Duin, Delft University of Technology, The Netherlands
Mario Figueiredo, Technical University of Lisbon, Portugal
Edwin Hancock, University of York, UK
Vittorio Murino, University of Verona, Italy
Marcello Pelillo (chair), University of Venice, Italy

Program Committee
Maria-Florina Balcan, Georgia Institute of Technology, USA
Manuele Bicego, University of Verona, Italy
Joachim Buhmann, ETH Zurich, Switzerland
Horst Bunke, University of Bern, Switzerland
Tiberio Caetano, NICTA, Australia
Umberto Castellani, University of Verona, Italy
Luca Cazzanti, University of Washington, Seattle, USA
Nicolo’ Cesa-Bianchi, University of Milan, Italy
Robert Duin, Delft University of Technology, The Netherlands
Francisco Escolano, University of Alicante, Spain
Mario Figueiredo, Technical University of Lisbon, Portugal
Ana Fred, Technical University of Lisbon, Portugal
Bernard Haasdonk, University of Stuttgart, Germany
Edwin Hancock, University of York, UK
Anil Jain, Michigan State University, USA
Robert Krauthgamer, Weizmann Institute of Science, Israel
Marco Loog, Delft University of Technology, The Netherlands
Vittorio Murino, University of Verona, Italy
Elzbieta Pekalska, University of Manchester, UK
Marcello Pelillo, University of Venice, Italy
Massimiliano Pontil, University College London, UK
Antonio Robles-Kelly, NICTA, Australia
Volker Roth, University of Basel, Switzerland
Amnon Shashua, The Hebrew University of Jerusalem, Israel
Andrea Torsello, University of Venice, Italy
Richard Wilson, University of York, UK

Organization Committee
Samuel Rota Bulo’ (chair), University of Venice, Italy
Nicola Rebagliati, University of Venice, Italy
Furqan Aziz, University of York, UK
Luca Rossi, University of Venice, Italy
Teresa Scantamburlo, University of Venice, Italy