Invited Talks.- Crossings between Curves with Many Tangencies.- Constant-Work-Space Algorithm for a Shortest Path in a Simple Polygon.- Approximation Algorithms for Art Gallery Problems in Polygons and Terrains.- The Hamiltonian Augmentation Problem and Its Applications to Graph Drawing.- Graph Drawing.- Small Grid Drawings of Planar Graphs with Balanced Bipartition.- Switch-Regular Upward Planar Embeddings of Trees.- A Global k-Level Crossing Reduction Algorithm.- Computational Geometry.- Computation of Non-dominated Points Using Compact Voronoi Diagrams.- Cutting a Convex Polyhedron Out of a Sphere.- A Simple Algorithm for Approximate Partial Point Set Pattern Matching under Rigid Motion.- Graph Algorithms I.- Acyclically 3-Colorable Planar Graphs.- Reconstruction Algorithm for Permutation Graphs.- Harmonious Coloring on Subclasses of Colinear Graphs.- Computational Biology and Strings.- Comparing RNA Structures with Biologically Relevant Operations Cannot Be Done without Strong Combinatorial Restrictions.- The 1.375 Approximation Algorithm for Sorting by Transpositions Can Run in O(nlogn) Time.- Parallel Algorithms for Encoding and Decoding Blob Code.- Combinatorial Optimization.- A Rooted-Forest Partition with Uniform Vertex Demand.- A Simple and Faster Branch-and-Bound Algorithm for Finding a Maximum Clique.- Graph Algorithms II.- On Some Simple Widths.- A New Model for a Scale-Free Hierarchical Structure of Isolated Cliques.- Approximation Algorithms.- The Covert Set-Cover Problem with Application to Network Discovery.- Variants of Spreading Messages.- On Finding a Better Position of a Convex Polygon Inside a Circle to Minimize the Cutting Cost.- Real Root Isolation of Multi-Exponential Polynomials with Application.- Parameterized Complexity.- FPT Algorithms for Connected Feedback Vertex Set.- A Simple and Fast Algorithm for Maximum Independent Set in 3-Degree Graphs.- Pathwidth and Searching in Parameterized Threshold Graphs.

WALCOM 2010, the 4th International Workshop on Algorithms and Com- tation, held during February 10 12, 2010 in Dhaka, Bangladesh, covered the areas of approximation algorithms, combinatorial algorithms, combinatorial - timization, computational Biology, computational geometry, data structures, graph algorithms, graph drawing, parallel and distributed algorithms, par- eterized complexity, network optimization, online algorithms, randomized - gorithms and string algorithms. The workshop was organized jointly by the Bangladesh Academy of Sciences (BAS) and Bangladesh University of En- neering and Technology (BUET), and the quality of the workshop was ensured by a ProgramCommittee comprising 25 researchersof internationalrepute from Australia,Bangladesh,Canada,France,Germany,Greece,HongKong,Hungary, India, Italy, Japan, Switzerland, Taiwan, UK and USA. Thisvolumecontains23contributedpapersandfourinvitedpaperspresented atWALCOM2010.TheCallforPapersreceivedanenthusiasticresponse,resu- ing in 60 submissions from 21 countries. The Program Committee thoroughly reviewed each of the 60 submissions and accepted 23 of them for presentation in the workshop after elaborate discussions on review reports. The image of the workshopwas highly enhanced by the four invited talks of eminent and we- knownresearchersTetsuoAsanoofJAIST,Japan,SubirKumarGhoshofTIFR, India, Giuseppe Liotta of University of Perugia, Italy and J anos Pach of EPFL Lausanne, Switzerland and R enyi Institute Budapest, Hungary.