3 citations · 9 across the 10 of their papers we have counts for
12 papers
Polyhedral volume ratios, Izmestiev's Colin de Verdiere matrices and Spectral Gaps
Ioannis Ivrissimtzis, Carsten Lange, Shiping Liu +1
We present a relation between volumes of certain lower dimensional simplices associated to a full-dimensional primal and polar dual polytope in R^k. We then discuss an application…
Race Bias Analysis of Bona Fide Errors in face anti-spoofing
Latifah Abduh, Ioannis Ivrissimtzis
The study of bias in Machine Learning is receiving a lot of attention in recent years, however, few only papers deal explicitly with the problem of race bias in face anti-spoofing.…
Use of in-the-wild images for anomaly detection in face anti-spoofing
Latifah Abduh, Ioannis Ivrissimtzis
The traditional approach to face anti-spoofing sees it as a binary classification problem, and binary classifiers are trained and validated on specialized anti-spoofing databases.…
A study of the effect of the illumination model on the generation of synthetic training datasets
Xin Zhang, Ning Jia, Ioannis Ivrissimtzis
The use of computer generated images to train Deep Neural Networks is a viable alternative to real images when the latter are scarce or expensive. In this paper, we study how the i…
Using theoretical ROC curves for analysing machine learning binary classifiers
Luma Omar, Ioannis Ivrissimtzis
Most binary classifiers work by processing the input to produce a scalar response and comparing it to a threshold value. The various measures of classifier performance assume, expl…
From Farey fractions to the Klein quartic and beyond
Ioannis Ivrissimtzis, David Singerman, James Strudwick
In his 1878/79 paper "Ueber die transformation siebenter ordnung der elliptischen functionen", Klein produced his famous 14-sided polygon representing the Klein quartic, his Rieman…
Watermark retrieval from 3D printed objects via synthetic data training
Xin Zhang, Ning Jia, Ioannis Ivrissimtzis
We present a deep neural network based method for the retrieval of watermarks from images of 3D printed objects. To deal with the variability of all possible 3D printing and image…
Watermark Retrieval from 3D Printed Objects via Convolutional Neural Networks
Xin Zhang, Qian Wang, Toby Breckon +1
We present a method for reading digital data embedded in planar 3D printed surfaces. The data are organised in binary arrays and embedded as surface textures in a way inspired by Q…
Trivalent expanders, -transformation, and hyperbolic surfaces
Ioannis Ivrissimtzis, Norbert Peyerimhoff, Alina Vdovina
We construct a new family of trivalent expanders tessellating hyperbolic surfaces with large isometry groups. These graphs are obtained from a family of Cayley graphs of nilpotent…
Simplicial Complex Entropy
Stefan Dantchev, Ioannis Ivrissimtzis
We propose an entropy function for simplicial complices. Its value gives the expected cost of the optimal encoding of sequences of vertices of the complex, when any two vertices be…
Trivalent expanders and hyperbolic surfaces
Ioannis Ivrissimtzis, Norbert Peyerimhoff, Alina Vdovina
We introduce a family of trivalent expanders which tessellate compact hyperbolic surfaces with large isometry groups. We compare this family with Platonic graphs and modifications…
Spectral representations of vertex transitive graphs, Archimedean solids and finite Coxeter groups
Ioannis Ivrissimtzis, Norbert Peyerimhoff
In this article, we study eigenvalue functions of varying transition probability matrices on finite, vertex transitive graphs. We prove that the eigenvalue function of an eigenvalu…