1. European Symposium on Algorithms – ESA
University of Ljubljana
Faculty of Computer and Information Science
European Symposium on Algorithms – ESA
ESA 2016 Conference review
Preparation: Ilcho Koteski

2. What is ESA? ESA is Annual European Symposium on Algorithms
Short history
The first ESA was held back in 1993 and since then it is one of the premier conferences on algorithms. It covers research in efficient algorithms and data structures in computer science, discrete applied mathematics, operations research and mathematical programming. Starting with ESA 2002, WAE (Workshop on Algorithm Engineering) was also incorporated into ESA. Since then the symposium has two tracks:
Design and Analysis Track (Design and mathematical analysis of algorithms)
Engineering and Application Track (Real-world applications, engineering and experimental analysis of algorithms)
Each track has its own program committee. Papers are submitted to a particular track, but the committees have the right to move papers between tracks.

3. When and where was last ESA?
The last ESA was held on 22 August – 24 August 2016, in Aarhus – Denmark
It was its 24th annual edition
Part of ALGO 2016 Conference
76 papers were accepted
Including these three:
Probabilistic Routing for On-Street Parking Search
Approximation and Hardness of Token Swapping
Faster External Memory LCP Array Construction

4. 1. Probabilistic Routing for On-Street Parking Search
Problem for solving: Street parking
NP-complete problem
Hamiltonian path
Three parameters taken into account:
Probability of finding parking spot
Walking distance
Duration
c(P)= 2(λ * distance + (1- λ) duration ) , λ E [0, 1]
Two algorithms as a solutions
Branch and Bound
Heuristic Search -> cost measure = 1.3* cost measure (Branch and Bound)

5. 2. Approximation and Hardness of Token Swapping
We have a graph G = (V, E) ; V= {1,...,n}
Every vertex has a token assigned T1,...,Tn
Problem for solving: How to find the shortest sequence of token swaps such that token Ti is placed on vertex i. More generalized version – color matching.
NP-complete problem
They prove that this can be solved in exponential time 2O(n log n) based on breadth-first search in an auxiliary graph.
4-Approximation algorithm
Approximation algorithm with approximation factor:
4 on general graphs
2 on trees
Constant k such that every polynomial time approximation algorithm has approximation factor of at least k.
Hardness: APX-hard

6. 3. Faster External Memory LCP Array Construction
Suffix array and LCP(Longest Common Prefix) array
Memory limitations (Data too big for RAM memory)
Problem for solving: How the suffix array to be augmented to LCP array in external memory
Known algorithm: LCPscan
Two Semi-External memory algorithms transformed into Fully External memory algorithms which compute LCP in:
Sparse-Φ :
SuccinctIrreducible:

7. -Thank you for your time