Leonard Johard

AI
10papers
28citations
Novelty18%
AI Score14

10 Papers

AIDec 20, 2017
Pseudorehearsal in actor-critic agents with neural network function approximation

Vladimir Marochko, Leonard Johard, Manuel Mazzara et al.

Catastrophic forgetting has a significant negative impact in reinforcement learning. The purpose of this study is to investigate how pseudorehearsal can change performance of an actor-critic agent with neural-network function approximation. We tested agent in a pole balancing task and compared different pseudorehearsal approaches. We have found that pseudorehearsal can assist learning and decrease forgetting.

NEJun 16, 2017
Self-adaptive node-based PCA encodings

Leonard Johard, Victor Rivera, Manuel Mazzara et al.

In this paper we propose an algorithm, Simple Hebbian PCA, and prove that it is able to calculate the principal component analysis (PCA) in a distributed fashion across nodes. It simplifies existing network structures by removing intralayer weights, essentially cutting the number of weights that need to be trained in half.

SEJun 14, 2017
Translating Event-B machines to Eiffel programs

Victor Rivera, JooYoung Lee, Manuel Mazzara et al.

Formal modelling languages play a key role in the development of software since they enable users to prove correctness of system properties. However, there is still not a clear understanding on how to map a formal model to a specific programming language. In order to propose a solution, this paper presents a source-to-source mapping between Event- B models and Eiffel programs, therefore enabling the proof of correctness of certain system properties via Design-by-Contract (natively supported by Eiffel), while still making use of all features of O-O programming.

SEApr 17, 2017
Initial steps towards assessing the usability of a verification tool

Mansur Khazeev, Victor Rivera, Manuel Mazzara et al.

In this paper we report the experience of using AutoProof to statically verify a small object oriented program. We identified the problems that emerged by this activity and we classified them according to their nature. In particular, we distinguish between tool-related and methodology-related issues, and propose necessary changes to simplify both tool and method.

AIApr 17, 2017
Pseudorehearsal in actor-critic agents

Marochko Vladimir, Leonard Johard, Manuel Mazzara

Catastrophic forgetting has a serious impact in reinforcement learning, as the data distribution is generally sparse and non-stationary over time. The purpose of this study is to investigate whether pseudorehearsal can increase performance of an actor-critic agent with neural-network based policy selection and function approximation in a pole balancing task and compare different pseudorehearsal approaches. We expect that pseudorehearsal assists learning even in such very simple problems, given proper initialization of the rehearsal parameters.

AIMar 21, 2017
Pseudorehearsal in value function approximation

Vladimir Marochko, Leonard Johard, Manuel Mazzara

Catastrophic forgetting is of special importance in reinforcement learning, as the data distribution is generally non-stationary over time. We study and compare several pseudorehearsal approaches for Q-learning with function approximation in a pole balancing task. We have found that pseudorehearsal seems to assist learning even in such very simple problems, given proper initialization of the rehearsal parameters.

SDNov 22, 2016
MOMOS-MT: Mobile Monophonic System for Music Transcription

Munir Makhmutov, Joseph Alexander Brown, Manuel Mazzara et al.

Music holds a significant cultural role in social identity and in the encouragement of socialization. Technology, by the destruction of physical and cultural distance, has lead to many changes in musical themes and the complete loss of forms. Yet, it also allows for the preservation and distribution of music from societies without a history of written sheet music. This paper presents early work on a tool for musicians and ethnomusicologists to transcribe sheet music from monophonic voiced pieces for preservation and distribution. Using FFT, the system detects the pitch frequencies, also other methods detect note durations, tempo, time signatures and generates sheet music. The final system is able to be used in mobile platforms allowing the user to take recordings and produce sheet music in situ to a performance.

DCAug 17, 2016
The BioDynaMo Project: Creating a Platform for Large-Scale Reproducible Biological Simulations

Lukas Breitwieser, Roman Bauer, Alberto Di Meglio et al.

Computer simulations have become a very powerful tool for scientific research. In order to facilitate research in computational biology, the BioDynaMo project aims at a general platform for biological computer simulations, which should be executable on hybrid cloud computing systems. This paper describes challenges and lessons learnt during the early stages of the software development process, in the context of implementation issues and the international nature of the collaboration.

NEAug 5, 2016
The BioDynaMo Project: a platform for computer simulations of biological dynamics

Leonard Johard, Lukas Breitwieser, Alberto Di Meglio et al.

This paper is a brief update on developments in the BioDynaMo project, a new platform for computer simulations for biological research. We will discuss the new capabilities of the simulator, important new concepts simulation methodology as well as its numerous applications to the computational biology and nanoscience communities.

NEJul 10, 2016
The BioDynaMo Project

Roman Bauer, Lukas Breitwieser, Alberto Di Meglio et al.

Computer simulations have become a very powerful tool for scientific research. Given the vast complexity that comes with many open scientific questions, a purely analytical or experimental approach is often not viable. For example, biological systems (such as the human brain) comprise an extremely complex organization and heterogeneous interactions across different spatial and temporal scales. In order to facilitate research on such problems, the BioDynaMo project (\url{https://biodynamo.web.cern.ch/}) aims at a general platform for computer simulations for biological research. Since the scientific investigations require extensive computer resources, this platform should be executable on hybrid cloud computing systems, allowing for the efficient use of state-of-the-art computing technology. This paper describes challenges during the early stages of the software development process. In particular, we describe issues regarding the implementation and the highly interdisciplinary as well as international nature of the collaboration. Moreover, we explain the methodologies, the approach, and the lessons learnt by the team during these first stages.