yusuke1997/dblp-id-title huggingface dataset:
Parallel Algorithm for Minimum Partial Dominating Set in Unit Disk Graph
Approximating the Restricted 1-Center in Graphs
On-Line Strategies for Evacuating from a Convex Region in the Plane
Structure of Towers and a New Proof of the Tight Cut Lemma
Combinatorial Optimization and Applications - 15th International Conference, COCOA 2021, Tianjin, China, December 17-19, 2021, Proceedings
Scheduling Jobs with Precedence Constraints to Minimize Peak Demand
XML Reconstruction View Selection in XML Databases: Complexity Analysis and Approximation Scheme
Fault-Tolerant Routing: k-Inconnected Many-to-One Routing in Wireless Networks
A Parallel Construction of Vertex-Disjoint Spanning Trees with Optimal Heights in Star Networks
Approximation Algorithms for Optimization Problems in Random Power-Law Graphs
On Problems Related to Absent Subsequences
On the Partition of 3-Colorable Graphs
On the Surface Area of the Asymmetric Twisted Cube
Linear Coherent Bi-cluster Discovery via Beam Detection and Sample Set Clustering
An Optimal Strategy for Static Black-Peg Mastermind with Two Pegs
A Comparative Analysis of NFT-Based Insurance Claim Management Systems Across EVM-Compatible Blockchain Platforms
Removing Undesirable Flows by Edge Deletion
Computing a Rectilinear Shortest Path amid Splinegons in Plane
The Eigen-Distribution of Weighted Game Trees
Related Machine Scheduling with Machine Speeds Satisfying Linear Constraints
Guarding Monotone Art Galleries with Sliding Cameras in Linear Time
Parameterized Approximation Algorithms for Some Location Problems in Graphs
On the k-colored Rainbow Sets in Fixed Dimensions
Stochastic Online Scheduling Revisited
An Online Model of Berth and Quay Crane Integrated Allocation in Container Terminals
A Two-Layers Heuristic Search Algorithm for Milk Run with a New PDPTW Model
A Parameterized Perspective on Packing Paths of Length Two
A Simpler and More Efficient Algorithm for the Next-to-Shortest Path Problem
Bounds for Nonadaptive Group Tests to Estimate the Amount of Defectives
Compact Visibility Representation of 4-Connected Plane Graphs
Computing a Tree Having a Small Vertex Cover
Two-Stage Submodular Maximization Under Curvature
A Region Growing Algorithm for Detecting Critical Nodes
New Insight into 2-Community Structures in Graphs with Applications in Social Networks
Selecting Sources for Query Approximation with Bounded Resources
Fast Diameter Computation Within Split Graphs
A Simple Algorithm for Scheduling Unit Jobs with Unknown Number of Machines
Secure Multiparty Computations Using the 15 Puzzle
Generalized Self-profit Maximization in Attribute Networks
Packing and Covering Triangles in Dense Random Graphs
Card-Based Secure Ranking Computations
On Complexities of Minus Domination
Approximation Algorithms for Maximum Coverage with Group Budget Constraints
Vertex-Uncertainty in Graph-Problems
Parameterized Graph Editing with Chosen Vertex Degrees
Data Summarization Beyond Monotonicity: Non-monotone Two-Stage Submodular Maximization
Realizability of Graphs as Triangle Cover Contact Graphs
On the Complexity of Resilience for Aggregation Queries
Cutting Stock with Rotation: Packing Square Items into Square Bins
Edge-Unfolding Polycubes with Orthogonally Convex Layers
On the Complexity of Some Colorful Problems Parameterized by Treewidth
Amortized Efficiency of Ranking and Unranking Left-Child Sequences in Lexicographic Order
Line Segment Covering of Cells in Arrangements
An Approximation Algorithm for the k-Median Problem with Uniform Penalties via Pseudo-Solutions
On Vertex-Edge and Independent Vertex-Edge Domination
Algorithms and Hardness Results for the Maximum Balanced Connected Subgraph Problem
The Union of Colorful Simplices Spanned by a Colored Point Set
An Improved Branching Algorithm for (n, 3)-MaxSAT Based on Refined Observations
On the Complexity of a Periodic Scheduling Problem with Precedence Relations
The Two Sheriffs Problem: Cryptographic Formalization and Generalization
Combinatorial Optimization and Applications - 17th International Conference, COCOA 2024, Beijing, China, December 6-8, 2024, Proceedings, Part II
Differentially Private Counting Queries on Approximate Shortest Paths
Optimal Strategy for Walking in Streets with Minimum Number of Turns for a Simple Robot
A Multi-pass Streaming Algorithm for Regularized Submodular Maximization
Improved Methods for Computing Distances Between Unordered Trees Using Integer Programming
Classification Statistics in RFID Systems
An I/O Efficient Algorithm for Minimum Spanning Trees
Algorithms for the Maximum Weight Connected k -Induced Subgraph Problem
Point Sets in the Unit Square and Large Areas of Convex Hulls of Subsets of Points
Computing Toolpaths for 5-Axis NC Machines
A Two-Stage Seeds Algorithm for Competitive Influence Maximization Considering User Demand
A Spectral Partitioning Algorithm for Maximum Directed Cut Problem
Randomized Online Algorithms for Set Cover Leasing Problems
Improved Algorithms for Computing Minmax Regret 1-Sink and 2-Sink on Path Network
Approximating k-Orthogonal Line Center
Nearly Complete Characterization of 2-Agent Deterministic Strategyproof Mechanisms for Single Facility Location in L p Space
An Iterative Algorithm of Computing the Transitive Closure of a Union of Parameterized Affine Integer Tuple Relations
Approximation Algorithms for Two Parallel Dedicated Machine Scheduling with Conflict Constraints
A Short Proof and Experimental Study of the Approximation Algorithm for Label s-t Cut
Approximation Algorithms for Max 3-Section Using Complex Semidefinite Programming Relaxation
Exact Computation of Strongly Connected Reliability by Binary Decision Diagrams
The Power of Rejection in Online Bottleneck Matching
The Price of Fairness for Budget-Feasible EF1 Allocations
A Practical Greedy Approximation for the Directed Steiner Tree Problem
Touring Convex Polygons in Polygonal Domain Fences
An Energy-Efficient Scheduling Method for Real-Time Multi-workflow in Container Cloud
Walking in Streets with Minimal Sensing
Symbolic Model Checking for Alternating Projection Temporal Logic
Attaining Equilibria Using Control Sets
Maximize the Probability of Union-Influenced in Social Networks
On the Mating Between a Polygonal Curve and a Convex Polygon
Parameterized and Approximation Algorithms for Finding Two Disjoint Matchings
Combinatorial Optimization and Applications - 16th International Conference, COCOA 2023, Hawaii, HI, USA, December 15-17, 2023, Proceedings, Part II
Congestion Games with Mixed Objectives
Capacitated Partial Inverse Maximum Spanning Tree Under the Weighted l ∞ -norm
Some Variations on Constrained Minimum Enclosing Circle Problem
Approximate Ellipsoid in the Streaming Model
Popularity on the Roommate Diversity Problem
Deleting Edges to Restrict the Size of an Epidemic: A New Application for Treewidth
Improved Algorithms for the Evacuation Route Planning Problem
Steiner Forests on Stochastic Metric Graphs
Two-Level Heaps: A New Priority Queue Structure with Applications to the Single Source Shortest Path Problem
On the Approximability of Partial VC Dimension
Scheduling with Rejection to Minimize the Makespan
Directed Width Parameters on Semicomplete Digraphs
Graph Simplification for Infrastructure Network Design
Mechanism Design for Facility Location Games with Candidate Locations
The Small Set Vertex Expansion Problem
Bases of Primitive Nonpowerful Sign Patterns
A New Approach to the Upper Bound on the Average Distance from the Fermat-Weber Center of a Convex Body
Ant Colony Optimization Metaheuristic for the Traffic Grooming in WDM Networks
Kolmogorov Structure Functions for Automatic Complexity in Computational Statistics
Exact and Approximation Algorithms for the Multi-depot Data Mule Scheduling with Handling Time and Time Span Constraints
A Comprehensive Reachability Evaluation for Airline Networks with Multi-constraints
On Connectedness of Solutions to Integer Linear Systems
On the Profit-Maximizing for Transaction Platforms in Crowd Sensing
Integer Programming Methods for Special College Admissions Problems
An Efficient Primal-Dual Algorithm for Fair Combinatorial Optimization Problems
Algorithms and Implementation for Interconnection Graph Problem
A 5/3-Approximation Algorithm for Joint Replenishment with Deadlines
Reducing Extension Edges of Concurrent Programs for Reachability Analysis
Tractable Feedback Vertex Sets in Restricted Bipartite Graphs
Separating Sublinear Time Computations by Approximate Diameter
On Strong Tree-Breadth
Primal Dual Algorithm for Partial Set Multi-cover
Two-Facility Location Games with a Minimum Distance Requirement on a Circle
Doctor Rostering in Compliance with the New UK Junior Doctor Contract
The Complexity of Testing Monomials in Multivariate Polynomials
Parameterized and Subexponential-Time Complexity of Satisfiability Problems and Applications
An Effective Hybrid Algorithm for the Circles and Spheres Packing Problems
On Structural Parameterizations of the Offensive Alliance Problem
Exact and Parameterized Algorithms for Edge Dominating Set in 3-Degree Graphs
An Improved Exact Algorithm for Undirected Feedback Vertex Set
A New Hybrid Algorithm for Feature Selection and Its Application to Customer Recognition
Orbital Independence in Symmetric Mathematical Programs
Global Internet Connectedness: 2002-2011
Combinatorial Optimization and Applications - 7th International Conference, COCOA 2013, Chengdu, China, December 12-14, 2013, Proceedings
Bipartite Communities via Spectral Partitioning
WDCS: A Weight-Based Distributed Coordinate System
List Dynamic Coloring of Sparse Graphs
Maximization of Monotone Non-submodular Functions with a Knapsack Constraint over the Integer Lattice
Hardness Results and Approximation Schemes for Discrete Packing and Domination Problems
The Location-routing Problem in the Pallet Pooling System Considering Carbon Emissions
On Construction of Almost-Ramanujan Graphs
A Potential Reduction Algorithm for Ergodic Two-Person Zero-Sum Limiting Average Payoff Stochastic Games
The Longest Subsequence-Repeated Subsequence Problem
A Fast and Effective Heuristic for Discovering Small Target Sets in Social Networks
Optimal Containment of Misinformation in Social Media: A Scenario-Based Approach
Combinatorics from Bacterial Genomes
Online Facility Assignment for General Layout of Servers on a Line
Conflict-Free Connection Numbers of Line Graphs
An Improved Approximation Algorithm for the Capacitated Multicast Tree Routing Problem
Kernel for Proper Helly Circular-Arc Vertex Deletion: Smaller and Simpler via Graph Isomorphism
Differentiable Discrete Optimization Using Dataless Neural Networks
Optimal Due Date Assignment Without Restriction and Convex Resource Allocation in Group Technology Scheduling
Fast Approximation Algorithms for Computing Constrained Minimum Spanning Trees
Rent Division Among Groups
Weak-Barrier Coverage with Adaptive Sensor Rotation
Making Multiple RNA Interaction Practical
An Improved Approximation Algorithm for the Bandpass-2 Problem
Super-Stability in the Student-Project Allocation Problem with Ties
A Lower Bound on Approximation Algorithms for the Closest Substring Problem
w-Centroids and Least (w, l)-Central Subtrees in Weighted Trees
On the Complexity of Detecting k-Length Negative Cost Cycles
Faster and Enhanced Inclusion-Minimal Cograph Completion
An Exact Algorithm for Non-preemptive Peak Demand Job Scheduling
An Experimental Study of Compressed Indexing and Local Alignments of DNA
Prediction Based Reverse Auction Incentive Mechanism for Mobile Crowdsensing System
Rectilinear Shortest Paths Among Transient Obstacles
Computing the Transitive Closure of a Union of Affine Integer Tuple Relations
Parameterized Complexity of Control and Bribery for d-Approval Elections
Incorporating Neural Point Process-Based Temporal Feature for Rumor Detection
Oriented Coloring of msp-Digraphs and Oriented Co-graphs (Extended Abstract)
Algorithms and Experimental Study for the Traveling Salesman Problem of Second Order
A Mathematical Programming Approach for Online Hierarchical Scheduling
Parameterized Complexity Classes Defined by Threshold Circuits: Using Sorting Networks to Show Collapses with W-hierarchy Classes
Algebraic Algorithm for Scheduling Data Retrieval in Multi-channel Wireless Data Broadcast Environments
A New Tractable Case of the QAP with a Robinson Matrix
On the Linearization of Scaffolds Sharing Repeated Contigs
Turán Graphs, Stability Number, and Fibonacci Index
Streaming with Minimum Space: An Algorithm for Covering by Two Congruent Balls
A Primal-Dual Approximation Algorithm for the Asymmetric Prize-Collecting TSP
A Dynamic Parameter Adaptive Path Planning Algorithm
Transporting Jobs through a Processing Center with Two Parallel Machines
The Connected p-Centdian Problem on Block Graphs
Approximating Bounded Job Start Scheduling with Application in Royal Mail Deliveries Under Uncertainty
Improved Bounds for Two Query Adaptive Bitprobe Schemes Storing Five Elements
A New Graph Parameter to Measure Linearity
Listing Center Strings Under the Edit Distance Metric
Propositional Projection Temporal Logic Specification Mining
Comprehensive Multi-view Subspace Clustering with Global-and-Local Representation Learning
Automatic Generation of Symmetry-Breaking Constraints
An Efficient PTAS for Parallel Machine Scheduling with Capacity Constraints
Combinatorial Optimization and Applications - 17th International Conference, COCOA 2024, Beijing, China, December 6-8, 2024, Proceedings, Part I
PATRON: A Unified Pioneer-Assisted Task RecommendatiON Framework in Realistic Crowdsourcing System
Approximate Shortest Paths in Polygons with Violations
Trip-Vehicle Assignment Algorithms for Ride-Sharing
The Optimization of Self-interference in Wideband Full-Duplex Phased Array with Joint Transmit and Receive Beamforming
The Price of Anarchy of Generic Valid Utility Systems
The Two-Center Problem of Uncertain Points on Trees
Minimum Energy Broadcast Routing in Ad Hoc and Sensor Networks with Directional Antennas
Scheduling for Electricity Cost in Smart Grid
On Open Rectangle-of-Influence Drawings of Planar Graphs
An Approximation Algorithm for Covering Vertices by 4 + -Paths
The Clique Corona Operation and Greedoids
Scheduling Problems in Cross Docking
Approximation Algorithm for the Minimum Directed Tree Cover
The Number of Shortest Paths in the ( n , k )-Star Graphs
Multicut on Graphs of Bounded Clique-Width
Approximation Algorithms for the Combination of Prize-Collecting Vertex Cover and Scheduling
Makespan Minimization with Machine Availability Constraints
The Generalized 3-Edge-Connectivity of Lexicographic Product Graphs
Indoor Localization via Candidate Fingerprints and Genetic Algorithm
K -Connected Target Coverage Problem in Wireless Sensor Networks
Faster Algorithms for Grid and Layered Drawings of Plane 3-Trees
Combinatorial Optimization and Applications - 11th International Conference, COCOA 2017, Shanghai, China, December 16-18, 2017, Proceedings, Part II
Repair Position Selection for Inconsistent Data
Polynomial Time Approximation Scheme for Connected Vertex Cover in Unit Disk Graph
Maximizing Revenues for On-Line Dial-a-Ride
A Constant-Factor Approximation Algorithm for the Link Building Problem
Some Graph Optimization Problems with Weights Satisfying Linear Constraints
On Maximizing the Difference Between an Approximately Submodular Function and a Linear Function Subject to a Matroid Constraint
Faster Algorithms for 1-Mappability of a Sequence
Scheduling Packets with Values and Deadlines in Size-Bounded Buffers
Mixed Degree-Degree Correlations in Directed Social Networks
Tracking Histogram of Attributes over Private Social Data in Data Markets
Energy-Constrained Drone Delivery Scheduling
Constant Factor Approximation for the Weighted Partial Degree Bounded Edge Packing Problem
A Note on Treewidth in Random Graphs
Feedback Vertex Sets on Tree Convex Bipartite Graphs
Routing and Scheduling Problems with Two Agents on a Line-Shaped Network
Energy Minimizing Vehicle Routing Problem
Algorithms on a Path Covering Problem with Applications in Transportation
GAMA: Genetic Algorithm for k-Coverage and Connectivity with Minimum Sensor Activation in Wireless Sensor Networks
A Semantic Model for Many-Core Parallel Computing
Maximizing One-Way Trading Revenue in Photovoltaic Energy Generation
NF-Based Algorithms for Online Bin Packing with Buffer and Item Size Limitation
Kinetic Red-Blue Minimum Separating Circle
A New Approach for Rearrangeable Multicast Switching Networks
Minimizing the Maximum Duty for Connectivity in Multi-Interface Networks
Top - K Query Retrieval of Combinations with Sum-of-Subsets Ranking
Improved Approximation Algorithm for Minimum Weight k-Subgraph Cover Problem
A Lagrangian Relaxation Approach for the Multiple Sequence Alignment Problem
Feature Selection Based on Graph Structure
Mixed-Case Community Detection Problem in Social Networks
A Framework for Overall Storage Overflow Problem to Maximize the Lifetime in WSNs
Optimizing Squares Covering a Set of Points
Data-Oblivious Graph Algorithms in Outsourced External Memory
The Bag-Based Search: A Meta-Algorithm to Construct Tractable Logical Circuits for Graphs Based on Tree Decomposition
Online Maximum k-Interval Coverage Problem
Characterizing Cycle-Complete Dissimilarities in Terms of Associated Indexed 2-Hierarchies
Simple Heuristics for the Rooted Max Tree Coverage Problem
Fair Selection of Clearing Schemes for Kidney Exchange Markets
Network Cost-Sharing Games: Equilibrium Computation and Applications to Election Modeling
Bounds for Static Black-Peg AB Mastermind
Defend the Clique-based Attack for Data Privacy
Online Bin Packing with (1, 1) and (2, R) Bins
Earliest Deadline First Is a 2-Approximation for DARP with Time Windows
Unfolding the Core Structure of the Reciprocal Graph of a Massive Online Social Network
Minimum Monotone Tree Decomposition of Density Functions Defined on Graphs
Real-Time Algorithm Scheme for n-Vehicle Exploration Problem
Improved Stretch Factor of Delaunay Triangulations of Points in Convex Position
Integer-Programming Bounds on Pebbling Numbers of Cartesian-Product Graphs
Improved Precise Fault Diagnosis Algorithm for Hypercube-Like Graphs
On the Constrained Steiner Strong Connectivity Augmentation Problem
An Approximation of the Zero Error Capacity by a Greedy Algorithm
New Results on a Family of Geometric Hitting Set Problems in the Plane
A Hybrid Large Neighborhood Search for Dynamic Vehicle Routing Problem with Time Deadline
Delay Management Problem: Complexity Results and Robust Algorithms
Combinatorial Optimization and Applications - 11th International Conference, COCOA 2017, Shanghai, China, December 16-18, 2017, Proceedings, Part I
Black and White Bin Packing Revisited
On k-Versus (k+1)-Leaf Powers
On the Twin-width of Outerplanar Graphs
Two Paths Location of a Tree with Positive or Negative Weights
Trees, Paths, Stars, Caterpillars and Spiders
An Introduction to Coding Sequences of Graphs
Faster Algorithms for Evacuation Problems in Networks with a Single Sink of Small Degree and Bounded Capacitated Edges
Approximation Algorithm for Min-max Correlation Clustering Problem with Penalties
A Local Search Approximation Algorithm for a Squared Metric k-Facility Location Problem
Characterizing Mechanisms in Obnoxious Facility Game
Graph Editing to a Given Neighbourhood Degree List is Fixed-Parameter Tractable
Cascading Critical Nodes Detection with Load Redistribution in Complex Systems
The 2-Median Problem on Cactus Graphs with Positive and Negative Weights
Restricted Edge Connectivity of Harary Graphs
V-Words, Lyndon Words and Substring circ-UMFFs
On Zero Forcing Number of Permutation Graphs
Parameterized Algorithms for Fixed-Order Book Drawing with Bounded Number of Crossings per Edge
On Unique Games with Negative Weights
Highway Preferential Attachment Models for Geographic Routing
The Fractional Strong Metric Dimension of Graphs
Further Improvement on Maximum Independent Set in Degree-4 Graphs
Improved Even Order Magic Square Construction Algorithms and Their Applications
On the Surface Area of the (n, k)-Star Graph
Efficient Method for Periodic Task Scheduling with Storage Requirement Minimization
Fair Maximization of Monotone Submodular Functions in Data Streams
Transforming Multi-matching Nested Traceable Automata to Multi-matching Nested Expressions
Going Weighted: Parameterized Algorithms for Cluster Editing
Heuristics for the Score-Constrained Strip-Packing Problem
Greedy Algorithm for Least Privilege in RBAC Model
Minimum Interval Cover and Its Application to Genome Sequencing
Observing the State of a Smart Grid Using Bilevel Programming
On Threshold BDDs and the Optimal Variable Ordering Problem
Minimum Weight Polygon Triangulation Problem in Sub-Cubic Time Bound
Online Scheduling on Two Parallel Machines with Release Times and Delivery Times
A Pseudo-Polynomial Time Algorithm for Solving the Knapsack Problem in Polynomial Space
An Efficient Algorithm for Chinese Postman Walk on Bi-directed de Bruijn Graphs
Approximation Algorithm for Minimizing the Weighted Number of Tardy Jobs on a Batch Machine
The Popular Matching and Condensation Problems Under Matroid Constraints
Searching Graph Communities by Modularity Maximization via Convex Optimization
Quickest Paths in Anisotropic Media
A Saturation Algorithm for Homogeneous Binomial Ideals
Algorithms for the Densest Subgraph with at Least k Vertices and with a Specified Subset
Constrained Stable Marriage with Free Edges or Few Blocking Pairs
Trajectory-Based Multi-hop Relay Deployment in Wireless Networks
Characterizing Graphs of Small Carving-Width
An Efficient Local Search Algorithm for Correlation Clustering on Large Graphs
Generalized Pyramidal Tours for the Generalized Traveling Salesman Problem
Deterministically Estimating Data Stream Frequencies
Improved Algorithms for Farthest Colored Voronoi Diagram of Segments
An Incentive Mechanism for Selfish Bin Covering
Efficient Algorithms for Ridesharing of Personal Vehicles
The Edge-Centered Surface Area of the Arrangement Graph
On the Competitiveness of Memoryless Strategies for the k-Canadian Traveller Problem
The Complexity of the Positive Semidefinite Zero Forcing
Editing Graphs to Satisfy Diversity Requirements
Star Routing: Between Vehicle Routing and Vertex Cover
Finding the Anti-block Vital Edge of a Shortest Path Between Two Nodes
Variants of Multi-resource Scheduling Problems with Equal Processing Times
Directed Path-Width of Sequence Digraphs
Alternating Lagrangian Decomposition Combining with Branch and Pricing for Robust and Integrated Airline Aircraft Routing and Crew Pairing
Machine Learning with Low-Resource Data from Psychiatric Clinics
On Adaptive Bitprobe Schemes for Storing Two Elements
Inapproximability after Uniqueness Phase Transition in Two-Spin Systems
Upper and Lower Bounds for Different Parameterizations of (n, 3)-MAXSAT
Improved MaxSAT Algorithms for Instances of Degree 3
The Price of Anarchy for the Load Balancing Game with a Randomizing Scheduler
Maximum Independent Set on B_1 B 1 -VPG Graphs
A LP-based Approximation Algorithm for generalized Traveling Salesperson Path Problem
Generalized Bidirectional Limited Magnitude Error Correcting Code for MLC Flash Memories
Optimal Speed Scaling with a Solar Cell - (Extended Abstract)
Evacuation of Rectilinear Polygons
The Spectral Radius and Domination Number of Uniform Hypergraphs
The Influence of Preprocessing on Steiner Tree Approximations
Efficiency of Dual Equilibria in Selfish Task Allocation to Selfish Machines
Fast Searching on Complete k-partite Graphs
A Grid Resource Discovery Method Based on Adaptive k -Nearest Neighbors Clustering
Hardness of Segment Cover, Contiguous SAT and Visibility with Uncertain Obstacles
On Unit Read-Once Resolutions and Copy Complexity
Directed Pathwidth and Palletizers
New Insights for Power Edge Set Problem
An Algorithm for Computing Virtual Cut Points in Finite Metric Spaces
Target Coverage with Minimum Number of Camera Sensors
Local Search Algorithms for k-Median and k-Facility Location Problems with Linear Penalties
Worst Case Analysis of a New Lower Bound for Flow Shop Weighted Completion Time Problem
A Spatio-Temporal Approach to the Discovery of Online Social Trends
Tackling Common Due Window Problem with a Two-Layered Approach
Hamiltonian Cycles in Covering Graphs of Trees