10th Athens Colloquium in Algorithms and Complexity

August 20-21, NTUA


Athens Colloquium in Algorithms and Complexity

August 20-21, 2015, National Technical University of Athens


ACAC is an annual meeting in Athens aiming to bring together researchers working in all areas of the theory of algorithms and computational complexity. It serves as a lively forum for presenting research results that are in a preliminary stage or have been recently accepted / presented in some major conference. Contributions may appear, fully or partially, in informal electronic proceedings available only to the participants (subject to authors' approval). The language of the workshop is English.


There are no registration fees. However, participants should register for administrative purposes, by filling the registration form no later than 18/8, starting on Monday, 15/6.


Participants interested in giving a presentation should register, providing a tentative title and a short abstract, either in the registration form (click the "Would you like to give a talk?" checkbox), or by sending an e-mail to, no later than 20/7. The organizers will make every possible effort so that all interested participants present their work (subject to scheduling constraints).

Topics of interest

Include, but are not limited to:

  • Analysis of Algorithms, Randomized and Approximation Algorithms
  • Computational Complexity
  • Data Structures
  • Cryptography
  • Graph Theory
  • Algorithmic Game Theory
  • Computational Geometry
  • Combinatorial Optimization
  • Algorithmic Algebra and Coding Theory
  • Theoretical Aspects of Databases
  • Computational Biology
  • Quantum Computing
  • Parallel and Distributed Computing
  • Machine Learning
  • Applications of Logic


  • Preliminary Program is announced here.

  • Important Dates

    Registration Deadline: 18/8
    Submission Deadline:    20/7

Organizing Committee

  • Dimitris Fotakis
  • Elias Koutsoupias
  • Evangelos Markakis
  • Ioannis Milis
  • Aris Pagourtzis
  • Stathis Zachos
  • Vassilis Zissimopoulos
  • Martha Sideri
  • Evripidis Markou

Local Arrangements

  • Antonis Antonopoulos
  • Eleni Bakali
  • Dimitris Fotakis
  • Aris Pagourtzis
  • Dimitris Tsipras
  • Stathis Zachos


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Thursday, August 20th

8:45 Registration - Coffee
9:15 Opening
9:30 - 10:30
Plenary Session    (Chair: Stathis Zachos)

On the Algorithmic Lovász Local Lemma and Acyclic Edge Coloring    Go to Abstract
Lefteris Kirousis, University of Athens & Computer Technology Institute and Press “Diophantus”
Abstract: The algorithm for Lovász Local Lemma by Moser and Tardos gives a constructive way to prove the existence of combinatorial objects that satisfy a system of constraints. We present an alternative probabilistic analysis of the algorithm that does not involve reconstructing the history of the algorithm. We apply our technique to improve the best known upper bound to acyclic chromatic index. Specifically we show that a graph with maximum degree $\Delta$ has an acyclic proper edge coloring with at most $\lceil 3.74(\Delta-1)\rceil+1$ colors, whereas the previously known best bound was $4(\Delta-1)$. The same technique is also applied to improve corresponding bounds for graphs with bounded girth. An interesting aspect of the latter application is that the probability of the ``undesirable” events do not have a uniform upper bound, i.e., it constitutes a case of the asymmetric Lovász Local Lemma.

Joint work by Ioannis Giotis, Kostas I. Psaromiligkos and Dimitrios M. Thilikos.
10:30 - 11:00 Coffee Break
11:00 - 12:30
Session 1    (Chair: Stathis Zachos)

Designing Networks with Good Equilibria under Uncertainty    Go to Abstract
Giorgos Christodoulou, University of Liverpool
Abstract: We consider the problem of designing network cost-sharing protocols with good equilibria under uncertainty. The underlying game is a multicast game in a rooted undirected graph with nonnegative edge costs. A set of k terminal vertices or players need to establish connectivity with the root. The social optimum is the Minimum Steiner Tree. We are interested in situations where the designer has incomplete information about the input. We propose two different models, the adversarial and the stochastic. In both models, the designer has prior knowledge of the underlying metric but the requested subset of the players is not known and is activated either in an adversarial manner (adversarial model) or is drawn from a known probability distribution (stochastic model).
Stable marriages with evolving preferences    Go to Abstract
Nikos Leonardos, LIAFA, Univ Paris Diderot, France
Abstract: We consider the classical Stable Marriages problem in a model introduced by Anagnostopoulos, Kumar, Mahdian, and Upfal, in 2011. The essential property of the model is that the input is not static but is dynamically changing. The changes are probabilistic and occur in discrete time-steps and the algorithm tries to detect them by querying the input in some predefined manner. The goal of the algorithm is to maintain an output which is dynamically changing and is sufficently "good" in expectation and with high probability. For the Stable Marriages problem we focus on the number of "unstable" pairs as a measure of the quality of the output.

Joint work with Varun Kanade and Frederic Magniez.
Enumeration of 2-level polytopes    Go to Abstract
Vissarion Fisikopoulos, Université libre de Bruxelles
Abstract: We propose the first algorithm for enumerating all combinatorial types of 2-level (a.k.a. compressed) polytopes of a given dimension d, and provide complete experimental results for d≤6. Our approach is based on new findings on 2-level polytopes, also presented here. In particular, we introduce the notion of a simplicial core, which allows us to reduce the problem to the enumeration of the closed sets of a discrete closure operator, along with some convex hull computations and isomorphism tests. (to appear in ESA'15)

Joint work with: Adam Bohn, Yuri Faenza, Samuel Fiorini, Marco Macchia, Kanstantsin Pashkovich
12:30 - 12:45 Coffee Break
12:45 - 13:45
Session 2    (Chair: Aris Pagourtzis)

On mobile agent verifiable problems    Go to Abstract
Evangelos Bampas, LaBRI, University of Bordeaux
Abstract: We consider decision problems that are solved in a distributed fashion by synchronous mobile agents operating in an unknown, anonymous network. Each agent has a unique identifier and an input string and they have to decide collectively a property which may involve their input strings, the graph on which they are operating, and their particular starting positions. Building on recent work by Fraigniaud and Pelc [LATIN 2012, LNCS 7256, pp. 362–374], we introduce several natural new computability classes allowing for a finer classification of problems below co-MAV or MAV, the latter being the class of problems that are verifiable when the agents are provided with an appropriate certificate. We provide inclusion and separation results among all these classes. We also determine their closure properties with respect to set-theoretic operations. Our main technical tool, which may be of independent interest, is a new meta-protocol that enables the execution of a possibly infinite number of mobile agent protocols essentially in parallel, similarly to the well-known dovetailing technique from classical computability theory.

Joint work with David Ilcinkas.
Collaborative Exploration by Energy-Constrained Mobile Robots    Go to Abstract
Christina Karousatou, Aix-Marseille University and CNRS, France
Abstract: We study the problem of exploration of a tree by mobile agents (robots) that have limited energy. The energy constraint bounds the number of edges that can be traversed by a single agent. Thus we need a team of agents to completely explore the tree and the objective is to minimize the size of this team. The agents start at a single node, the designated root of the tree and the height of the tree is bounded by the energy bound B. We provide an exploration algorithm without any knowledge about the tree and we compare our algorithm with the optimal offline algorithm that has complete knowledge of the tree. Our algorithm has a competitive ratio of O(logB), independent of the number of nodes in the tree. We also show that this is the best possible competitive ratio for exploration of unknown trees.
13:45 - 15:00 Lunch Break
15:00 - 16:00
Session 3    (Chair: Vangelis Markakis)

Improving Selfish Routing for Risk-Averse Players    Go to Abstract
Thanasis Lianeas, University of Texas at Austin
Abstract: We investigate how and to which extent one can exploit risk-aversion and modify the perceived cost of the players in selfish routing so that the Price of Anarchy (PoA) wrt. the total latency is improved. The starting point is to introduce some small random perturbations to the edge latencies so that the expected latency does not change, but the perceived cost of the players increases, due to risk-aversion. We adopt the simple model of γ-modifiable routing games, a variant of selfish routing games with restricted tolls. We prove that computing the best γ-enforceable flow is NP-hard for parallel-link networks with affine latencies and two classes of heterogeneous risk-averse players. On the positive side, we show that for parallel-link networks with heterogeneous players and for series-parallel networks with homogeneous players, there exists a nicely structured γ-enforceable flow whose PoA improves fast as γ increases. We show that the complexity of computing such a γ-enforceable flow is determined by the complexity of computing a Nash flow for the original game. Moreover, we prove that the PoA of this flow is best possible in the worst-case, in the sense that there are instances where (i) the best γ-enforceable flow has the same PoA, and (ii) considering more flexible modifications does not lead to any improvement on the PoA.
Pushing the Envelope in Graph Compression   Go to Abstract
Katia Papakonstantinopoulou, University of Athens
Abstract: We improve the state-of-the-art method for the compression of web and other similar graphs by introducing an elegant technique which further exploits the clustering properties observed in these graphs. The analysis and experimental evaluation of our method shows that it outperforms the currently best method of Boldi et al. by achieving a better compression ratio and retrieval time. Our method exhibits vast improvements on certain families of graphs, such as social networks, by taking advantage of their compressibility characteristics, and ensures that the compression ratio will not worsen for any graph, since it easily falls back to the state-of-the-art method.
16:00 - 16:15 Coffee Break
16:15 - 17:45
Session 4    (Chair: Dimitris Fotakis)

Who to Trust for Truthfully Maximizing Welfare?    Go to Abstract
Emmanouil Zampetakis, Massachusetts Institute of Technology
Abstract: We introduce a general approach based on selective verification and obtain approximate mechanisms without money for maximizing the social welfare in the general domain of utilitarian voting. Having a good allocation in mind, a mechanism with verification selects few critical agents and detects, using a verification oracle, whether they have reported truthfully. If yes, the mechanism produces the desired allocation. Otherwise, the mechanism ignores any misreports and proceeds with the remaining agents. We obtain randomized truthful (or almost truthful) mechanisms without money that verify only O(lnm/ϵ) agents, where m is the number of outcomes, independently of the total number of agents, and are (1−ϵ)-approximate for the social welfare. We also show that any truthful mechanism with a constant approximation ratio needs to verify Ω(logm) agents. A remarkable property of our mechanisms is emph{robustness}, namely that their outcome depends only on the reports of the truthful agents.
On the Efficiency of All-Pay Mechanisms    Go to Abstract
Alkmini Sgouritsa, University of Liverpool
Abstract: We study the inefficiency of mixed equilibria, expressed as the price of anarchy, of all-pay auctions in three different environments: combinatorial, multi-unit and single-item auctions. First, we consider item-bidding combinatorial auctions where m all-pay auctions run in parallel, one for each good. For fractionally subadditive valuations, we strengthen the upper bound from 2 to 1,82 by proving some structural properties that characterize the mixed Nash equilibria of the game. Next, we design an all-pay mechanism with a randomized allocation rule for the multi-unit auction. We show that, for bidders with submodular valuations, the mechanism admits a unique, 75% efficient, pure Nash equilibrium. The efficiency of this mechanism outperforms all the known bounds on the price of anarchy of mechanisms used for multi-unit auctions. Finally, we analyze single-item all-pay auctions motivated by their connection to contests and show tight bounds on the price of anarchy of social welfare, revenue and maximum bid.
Manipulation of h-index, g-index, i10-index by merging articles    Go to Abstract
Chrystalla Pavlou, University of Oxford
Abstract: In the academic word different measures are used to quantify the productivity and the impact of a researcher. The h-index, g-index and i10-index are examples of popular scientific impact indices that are computed in many article databases. Although these indices are widely used, there have been some observations about how someone can manipulate them. Extending the model proposed by Bevern et al. (2014), we investigate whether it is easy for a researcher to improve his g-index and i10-index by means of the merge operation. We also study the manipulation of h-index, g-index and the i10-index under a model that takes the social network of the researcher into account. Specifically, we study the case where a researcher wants to improve his target index without affecting a second researcher's index and two adversarial scenarios. In the first case a researcher wants to improve his target index in a way that does not improve his opponent's index and in the second case a researcher wants to harm his opponent's index in a way that does not harm his own index.
17:45 - 18:00 Short Break
18:00 - 19:00
Session 5    (Chair: Vassilis Zissimopoulos)

Cost-sharing models in Participatory Sensing    Go to Abstract
Giorgos Birmpas, Athens University of Economics and Business
Abstract: In Smart City and Participatory Sensing initiatives the key concept is for user communities to contribute sensor information and form a body of knowledge that can be exploited by innovative applications and data analytics services. A key aspect in all such platforms is that sensor information is not free but comes at a cost. As a result, these platforms may suffer due to insufficient sensor information made publicly available if applications do not share efficiently the cost of the sensor information they consume. We explore the design of specialized market mechanisms that match demand to supply while taking into account important positive demand externalities: sensors are digital goods and their cost can be shared by applications. We focus on the buyer side and define different demand models according to the flexibility in choosing sensor data for satisfying application needs. We then investigate the properties of various cost-sharing mechanisms with respect to efficiency and budget balance. In doing so, we also propose and study a new mechanism, which although lacks strategyproofness, it exhibits important efficiency improvement along with certain fairness properties.
Aggregating partial rankings with applications to peer grading in MOOCs    Go to Abstract
Alexandros Voudouris, University of Patras
Abstract: We investigate the potential of using ordinal peer grading for the evaluation of students in massive online open courses (MOOCs). According to such grading schemes, each student receives a few assignments (by other students) which she has to rank. Then, a global ranking is produced by combining the individual ones. This is a novel application area for social choice concepts and methods where the important problem to be solved is as follows: how should the assignments be distributed so that the collected individual rankings can be easily merged into a global one that is as close as possible to the ranking that represents the relative performance of the students in the assignment? Our main theoretical result suggests that using very simple ways to distribute the assignments so that each student has to rank only k of them, a Borda-like aggregation method can recover a 1-O(1/k) fraction of the true ranking when each student correctly ranks the assignments she receives. Experimental results indicate that this method works even better in practice and is extremely robust even when students have imperfect capabilities as graders. Our results provide strong evidence that ordinal peer grading can be a highly effective and scalable solution for evaluation in MOOCs.

Friday, August 21st

9:30 - 11:00
Session 6    (Chair: Ioannis Milis)

Mobile Agents Rendezvous in Rings, in spite of a Malicious Agent    Go to Abstract
Euripides Markou, University of Thessaly
Abstract: A number of ‘honest’ mobile agents need to gather at a node of a ring network while a malicious agent can move at the network and block the agents preventing them from gathering. The malicious agent is assumed to be arbitrarily fast, has full knowledge of the network and it cannot be exterminated by the honest agents. The honest agents are asynchronous and anonymous finite automata, they have no knowledge about the network, apart from its topology, and they can communicate only when they meet at a node. We solve the problem for any number of agents in oriented ring networks and for any odd number of agents in unoriented ring networks, while we show that rendezvous is impossible for an even number of agents in unoriented rings. Our model lies between the more powerful but static fault model of ‘black holes’ (which can even destroy the agents), and the less powerful but mobile fault model of ‘Byzantine agents’ (which can only imitate the honest agents).
Efficient Money-Burning in General Domains    Go to Abstract
Dimitris Tsipras, National Technical University of Athens
Abstract: We study mechanism design where the payments charged to the agents are not in the form of monetary transfers, but effectively burned. In this setting, the objective shifts from maximizing social welfare, to maximizing social utility, i.e. the social welfare minus the payments charged. We consider the general setting with m discrete outcomes and n multidimensional agents. We present mechanisms that provide optimal worst case guarantees with respect to maximizing social utility, while simultaneously approximating the optimal social welfare within a constant factor. Such mechanisms are obtained by defining a maximization problem on a suitably chosen smooth surface of probability distributions. This approach leads to a closed-form, smooth mechanism and we believe to be of independent interest.
Welfare Ratios for One-sided Matching Mechanisms    Go to Abstract
Aris Filos-Ratsikas, University of Oxford
Abstract: We study the Price of Anarchy of mechanisms for the fundamental problem of social welfare maximization in one-sided matching settings, when agents have general cardinal preferences over a finite set of items. We show that the two most well-studied mechanisms in literature, Probabilistic Serial and Random Priority have a Price of Anarchy of O(sqrt(n)). We complement our results with a lower bound of Ω(sqrt(n)) on the Price of Anarchy of all mechanisms. As a result, we conclude that these mechanisms are optimal. We extend our lower bound to the Price of Stability of all mechanisms that satisfy a mild "proportionality-like" property.
11:00 - 11:30 Coffee Break
11:30 - 13:00
Session 7    (Chair: Euripides Markou)

An introduction to utility elicitation    Go to Abstract
Angelina Vidali, Pierre and Marie Curie University
Abstract: I present some of the standard methods in the literature for eliciting the utility of a user in the expected utility model as well as in the more realistic model of prospect theory e.g. when users are risk-averse.
The SYNAISTHISI Project: Using Multi-Agent Systems Technologies in Resource Allocation    Go to Abstract
Ioannis Vetsikas, NCSR Demokritos
Abstract: The proliferation of mobile smart devices and the Internet of Things (IoT) vision brings about a number of opportunities for new services and business models. Taking a cue from cloud computing, we develop the SYNAISTHISI platform: it interfaces with heterogeneous components (devices or biological entities) that offer sensing, processing and actuator capabilities and integrate them as reusable services that are managed and easily “weaved” into complex applications. In this talk, we will briefly examine two of the key (multi-agent) technologies used in the platform. First, to create complex cyber-physical systems (CPS) on-demand from available services, we develop agent strategies and mechanisms that facilitate the allocation of services to specific CPS. More specifically, the customers submit blueprints of CPS to be created together with a budget and their agent bids for possible services (offered by service providers) that maximize their customers’ expected profit. A mechanism with desirable properties (e.g. efficient, fair) is developed that matches these services to customers, as well as strategies for the customer agents that allow them to deal with uncertainties, such as failing services or realizing at run time that more services might be necessary than those invoked initially. Second, for one of the SYNAISHISI pilots, pertaining to the smart grid, our goal is to incentivize the usage of renewable energy and to flatten the demand from traditional power plants (coal etc). To achieve this, we develop multi-agent based technologies for Demand Reduction (DR) and Demand Side Management (DSM). Compared to existing DR/DSM technologies though our approach is not centralized, but rather each actor (e.g. household and end user) optimizes their energy usage individually. To coordinate the process we developed mechanisms (giving pricing or social incentives through the appropriate gamification), so that the optimal action for users and their agents is to shift and/or reduce their demand to coincide with times when energy is more abundant and available from renewable energy sources. The benefits of this approach are increased privacy, and also that no central system imposes a decision to the user, but rather the user desires herself to take the actions that are good for the overall system.
Scheduling MapReduce Jobs and Data Shuffle on Unrelated Processors    Go to Abstract
Georgios Zois, Athens University of Economics and Business
Abstract: We propose a constant approximation algorithm for generalizations of the Flexible Flow Shop (FFS) problem which form a realistic model for nonpreemptive scheduling in MapReduce systems. Our results concern the minimization of the total weighted completion time of a set of MapReduce jobs on unrelated processors and improve substantially on the model proposed by Moseley et al. (SPAA 2011) in two directions: (i) we consider jobs consisting of multiple Map and Reduce tasks, which is the key idea behind MapReduce computations, and (ii) we introduce into our model the crucial cost of the data shuffle phase, i.e., the cost for the transmission of intermediate data from Map to Reduce tasks. Moreover, we experimentally evaluate our algorithm compared with a lower bound on the optimal cost of our problem as well as with a fast algorithm, which combines a simple online assignment of tasks to processors with a standard scheduling policy. As we observe, for random instances that capture data locality issues, our algorithm achieves a better performance.
13:00 - 15:00 Lunch Break
15:00 - 15:45
Session 8    (Chair: Stathis Zachos)

Stochastic Congestion Games with Risk-Averse Players    Go to Abstract
Haris Angelidakis, Toyota Technological Institute at Chicago
Abstract: Congestion games ignore the stochastic nature of resource delays and the risk-averse attitude of the players to uncertainty. To take these into account, we introduce two variants of atomic congestion games, one with stochastic players, where players assign load to their strategies independently with some probability, and another with stochastic edges, where the latency functions are random. In both variants, the players are risk-averse, and their individual cost is a player-specific quantile of their delay distribution. We focus on parallel-link networks and prove that stochastic congestion games on such networks admit an efficiently computable pure Nash equilibrium if the players have either the same risk attitude or the same participation probabilities, and also admit a potential function if the players have the same risk attitude. On the negative side, there exist games with players of different risk attitudes that are not potential. As for the inefficiency of equilibria, for parallel-link networks with n players and linear delays, the Price of Anarchy is Θ(n) and may be unbounded, in case of stochastic edges.

This is joint work with Dimitris Fotakis and Thanasis Lianeas.
15:45 - 16:15 Coffee Break
16:15 - 17:00
Session 9    (Chair: Stathis Zachos)

System Fragility under Load Redistribution from an Attacker's Perspective    Go to Abstract
Evangelos Chatziafratis, National Technical University of Athens
Abstract: System Robustness and System Fragility are used when dealing with the problem of finding out how robust (resistant to failure) is a system in case some of its parts are not working as expected and are malfunctioning. System robustness is interested in the behaviour of computer systems, electrical and mechanical systems, energy systems, network security etc. It is an important area of research and it has many applications in today's extremely connected world of the Internet and in the efforts for constructing complex systems such as the smart energy grid etc. In addition, it is also important for the design and study of the so-called Interdependent Systems. In this thesis, we study the problem of cascading failures: that is the situation in which we have an attack that destroys some part of the system and these failures may lead to further failures to other parts of the system. The main reason of this cascading effect and interconnection between different nodes are the possible node dependencies (e.g. power supply) or the load redistribution that is happening when an attacked node fails. The load redistribution may be equal among all remaining nodes or may be targeted to selected few of the remaining nodes (e.g. neighbouring nodes). Some of the aspects considered here for the load redistribution problem are also related to virus propagation, social networks and the well-known problem of influence maximization. At the beginning of this thesis, we present recent research in the area of system robustness and the different techniques that have been developed and that are used to address the problem. We study cases where the initial failures are random (e.g. due to a natural disaster) or the failures are because of strategically planned attacks (e.g. terrorist attacks). We also present a new approach to system robustness based on loads and capacities with cascading failures and we give proofs for the hardness of finding the best strategy to attack the system, if we have constraints on the number of attacks and on the magnitude of these attacks. We present some greedy algorithms that may be intuitive, but are not guaranteed to give a good solution and may in fact have really bad behaviour. Afterwards, we continue by imposing extra constraints on the values of the system's loads and capacities in order to acquire less pathological cases that are most frequently seen in real situations and we give efficient algorithms that find the optimal solution from an attacker's perspective. Finally, we conclude this thesis by briefly describing the future work that needs to be done in order to address some interesting problems that we came across during the preparation of this work.
17:00 - 17:15 Short Break
17:15 - 18:15
Short Sessions
18:15 Closing
21:00 Dinner


First Name Last Name Affiliation
GeorgiosAmanatidisAthens University of Economics and Business
AntoniosAngelakisECE NTUA
KonstantinosAngelopoulosUniversity of Trento
ChristosAslanoglouDI, UoA
EvangelosBampasLaBRI, University of Bordeaux
EleniBatziouNational Technical University of Athens
IoannisCaragiannisUniversity of Patras
XenophonChatzigeorgiouECE, UoPatra
GiorgosChristodoulouUniversity of Liverpool
IoannisDiamantisNational Technical University of Athens
RizartDonaDi, UoA
ArisFilos-RatsikasUniversity of Oxford
VissarionFisikopoulosUniversité libre de Bruxelles
GeorgeFotopoulosIEK KSINI / Open University of Patra
PanagiotisFotopoulosUniversity of Athens
MyrtoGalenianouUniversity of Athens
ChristinaGiannoulaStudent at School of Electrical and Computer Engineering - N.T.U.A.
VasilisGkatzelisStanford University
GeorgiaGkiokaECE student
VasilisGoumasECE, NTUA
Panagiotis GrontasNtua
Anthimos-VardisKandirosNational Technical University of Athens
ChrysostomosKaniourasECCE, NTUA
PavlosKapoutsisECCE, NTUA
Aggelos-DionysiosKapposNational and Kapodistrian University of Athens
GrigorisKaragiorgosTEI of Peloponnese
AnnaKarasoulouUniversity of Athens
ChristinaKarousatouAix-Marseille University and CNRS, France
VasilikiKontouraNational Technical University of Athens
EugeniaKotzapanagiotouUniversity of Patras
KonstantinosKoukasDI, UoA
GeorgeKrimpasUniversity of Patras
NickKrimpasUniversity of Patras
KonstantinosLentzosUniversität Konstanz
NikosLeonardosLIAFA, Univ Paris Diderot, France
ThanasisLianeasUniversity of Texas at Austin
JohnLivieratosGraduate Student
VasilisMargonisUniversity of Patras
VangelisMarkakisAthens University of Economics and Business
EuripidesMarkouUniversity of Thessaly
Orestis MelkonianNational and Kapodistrian University of Athens
StavrosMessarisUniversity of Athens (Undergrad Mathematics Student)
AlexandrosMetaxasECE, NTUA
Faidra GeorgiaMonachouNTUA
VassilikiNikolaouECE, NTUA
MichalisPapadopoullosECE NTUA
PlatonPapadopoulosNTUA undergraduate
KatiaPapakonstantinopoulouUniversity of Athens
IoannisPapatsorisUniversity of Athens
VangelisPaschosLAMSADE, Université Paris-Dauphine
ChrystallaPavlouUniversity of Oxford
MatoulaPetroliaUniversity of Nantes
MariaPetropanagiotakiGraduate Student
ManolisPitsikalisdi uoa
DimitriosPolitisAristotle university of Thessaloniki
GeorgePolykratisPhysics Department, University of Athens
IoannisPsarrosUniversity of Athens
JohnRetsas Undergraduate student
AgapiRissakiECE NTUA
MarioSaldingerNational and Kapodistrian University of Athens
EleniSapountziUniversity of Thessaly
AlkminiSgouritsaUniversity of Liverpool
LamprosSmyrnaiosComputer Science
OrestisTelelisUniversity of Piraeus
Orfeas StefanosThyfronitis LitosECE NTUA
EfthymiosTsakalerisBank of Greece
EliasTsigaridasINRIA Paris
Mustafa KemalTuralIndustrial Engineering Department, Middle East Technical University
IoannaTziallaECE NTUA
GrigoriosVelegkasECE, NTUA
IoannisVetsikasNCSR Demokritos, Greece
AngelinaVidaliPierre and Marie Curie University
EleftheriaVolianakiUniversity of Patras
Alexandros VoudourisUniversity of Patras
ChristosVrachasUniversity of Athens
VassilisZissimopoulosUniversity of Athens
GeorgiosZoisAthens University of Economics and Business
ilias kotsireasWilfrid Laurier University, Waterloo, Ontario, Canada
stavrospetsalakisDIT, UoA
ΔημήτρηςΔημητρίουΤμήμα Πληροφορικής ΕΚΠΑ
ΑπόστολοςΚυτέαςΦοιτητής ΣΗΜΜΥ
ΠαναγιώτηςΠουραΐμηςΣπουδαστής ΣΗΜΜΥ ΕΜΠ


ACAC15 will take place in the Multimedia Amphitheater of the National Technical University of Athens, located in the basement of the building of NTUA's Central Library. See the map below:

You can arrive at the Central Library by various ways:

By public transport:

The easiest way is by taking the Blue Metro line and getting off at the "ΚΑΤΕΧΑΚΗ" station. Then take the bus 242, get off at stop "ΘΥΡΩΡΕΙΟ" and walk 5 minutes towards the Central Library.
Another option is to take the bus 140 from the "ΚΑΤΕΧΑΚΗ" metro station and get off at stop "ΠΟΛΥΤΕΧΝΕΙΟΥΠΟΛΗ". Then get into the campus and walk 10 minutes towards the Central Library.

By car:

You can use this google map to get directions from Alimou-Katechaki Avenue.