Table of Contents

• 1. Files
  • 1.1. data subdirectory
  • 1.2. data_formatting subdirectory
  • 1.3. railway_solvers subdirectory
  • 1.4. qubos subdirectory
  • 1.5. solutions subdirectory
2. Main directory

Please edit the org which is in Emacs org markup. The md5 will be generated from that.

Files

data subdirectory

These are the raw input data.

data_formatting subdirectory

Scripts to parse the input data and generate inputs in the required format.

A test can be run like that:

python3 -m pytest

in this directory. The data_formatting subdirectory (same name as its parent) is the parser module.

railway_solvers subdirectory

These are the actual solvers. A test can be run like that:

python3 -m pytest

in this directory. The railway_solvers subdirectory (same name as its parent) is the solver module.

qubos subdirectory

There are pickles files containing QUBOs for particuler use cases.

solutions subdirectory

There are pickles files containing results of D-Wave solutions via:

• simulations,
• real annelaing,
• hybrid solvers

Main directory

There are following railway dispatching problems.

real railway problem

The module solve_real_problem.py is used to solve real problem of railway dispatching on the core of Silesian railway network. The script solves the problem via classical linear programming, D-Wave quantum approach, D-Wave hybrid or simulation approach.

Input:

--case  particular case of railway dispatching problem (0 to 9 is supported, default 1)
--category the category of time variables "Integer" yields ILP problem "Continious" yields MLP problem (default "Integer")
--solve_lp  chose PuLp solver, e.g. 'PULP_CBC_CMD'  'GUROBI_CMD' 'CPLEX_CMD' 
--solve_quantum   chose quantum or quantum inspired solver, "sim" - D-Wave simulation, "real" - D-Wave QPU, "bqm" - D-Wave hybrid bqm solver, "cqm" - D-Wave hybrid cqm solver
--min_t minimal time parameter for D-Wave hybrid solver in (rescalled) seconds (5 default)
--runs number of experiments (runs in the quantum case)

Output:

Solutions of quantum D-Wave approach (i.e. quantum, hybrid or simulation via --solve_quantum) are saved in solutions_quantum subdirectory as pickle files. Solutions of linear programming approach are printed.

Example use:

• classical programming

python solve_real_problem.py --case 0 --category Integer --solve_lp PULP_CBC_CMD

• D-Wave quantum or hybrid approach

python solve_real_problem.py --case 0 --category Integer --solve_quantum cqm --min_t 5 --runs 5

Difficulty of dispatching problem grows with the case number. Case 0, no disturbances. In Cases 1 to 3 some trains are delayed, but they follow their original routes. Cases 4 to 9 concerns also a priory changes trains' routes e.g. due to some track failure.

In solutions_quantum the script tmin_plot.py plots the sweep over t_min parameter.

To save / display result timetable use optional parameter --show_timetable 1 , e.g.:

python solve_real_problem.py --case 0 --category Integer --solve_lp PULP_CBC_CMD --show_timetable 1.

In the case of quantum computiong it will read data from file, i.e.:

python solve_real_problem.py --case 0 --category Integer --solve_quantum cqm --min_t 5 --runs 5 --show_timetable 1

Generic problem

The generic example concerns dense passenger traffic (generic) on the KO-GLC part of the Silesian railway network. For each case there are 12 instances of various delays of trains at start.

Input:

--case  particular case of railway dispatching problem (1 to 3 is supported)
--category the category of time variables "Integer" yields ILP problem "Continious" yields MLP problem (default "Integer")
--solve_lp  chose PuLp solver, e.g. 'PULP_CBC_CMD'  'GUROBI_CMD' 'CPLEX_CMD'
--solve_quantum  chose quantum or quantum inspired solver, "sim" - D-Wave simulation, "real" - D-Wave QPU, "bqm" - D-Wave hybrid bqm solver, "cqm" - D-Wave hybrid cqm solver
--min_t minimal time parameter for D-Wave hybrid solvers (hyb, cqm) in seconds (5 default)
-- penalty - the penalty value for QUBO creation, applicable only for bqm (hyb, sim, real), by default 2.5

Particular description of cases:

• case 1, there are no disruptions inside the analysed (double track) line, and we use cyclic timetable of 3 hours i.e. with 59 trains, particular instances concern delays of various trains at start;
• case 2, we assume that one track between RCB and ZZ is closed, hence the line becomes partially single track and additional we use cyclic timetable of 2 hours i.e. with 40 trains, particular instances concern delays of various trains at start;
• case 3, line is analysed as hypothetical single track line of 3 hours and 21 trains, particular instances concern delays of various trains at start.

Output:

Solutions of quantum and classical approaches are saved in results_KO_GLC subdirectory as pickle files.

In results_KO_GLC there is the plotting script fast_plot.py

Example use:

• clasical programming

python3 solve_KO_GLC_problems.py --solve_lp PULP_CBC_CMD --case 1 --category Integer

• D-Wave quantum or hybrid approach

python3 solve_KO_GLC_problems.py --solve_quantum cqm --case 1 --category Integer --min_t 5

In the case if not CQM solver is used, the paenalty for QUBO can be assigned:

python3 solve_KO_GLC_problems.py --solve_quantum cqm --case 1 --category Integer --min_t 5, --penalty 2.5

Problem from "Quantum Annealing in the NISQ Era: Railway Conflict Management"

K. Domino, M. Koniorczyk,K. Krawiec, K. Jałowiecki, S. Deffner, B. Gardas Entropy 2023, 25, 191.

The module:

wisla_problems.py 

is the test module for for case 1 problem from mentioned work.

Input:

--solve_lp  chose PuLp solver, e.g. 'PULP_CBC_CMD'  'GUROBI_CMD' 'CPLEX_CMD'
--solve_quantum   chose quantum or quantum inspired solver, "sim" - D-Wave simulation, "real" - D-Wave, "bqm" - D-Wave hybrid from QUBO, "cqm" - D-Wave hybrid cqm
--min_t minimal time parameter for D-Wave hybrid solver in seconds (5 default)

Output

Solutions of quantum approach (i.e. by -solve_quantum) are saved in solutions_quantum/wisla subdirectory as pikle files. Solutions of linear programming apprach are printed.

Example use:

• linear programming

python wisla_problems.py --solve_lp PULP_CBC_CMD

• D-Wave quantum approach

python wisla_problems.py --solve_quantum real

• D-Wave hybrid (cqm) approach

python wisla_problems.py --solve_quantum cqm --min_t 5

To save / display result timetable use optional parameter --show_timetable 1 , e.g.:

python wisla_problems.py --solve_lp PULP_CBC_CMD --show_timetable 1.

In the case of quantum computiong it will read data from file, i.e.:

python wisla_problems.py --solve_quantum sim --show_timetable 1

Citing this work

The code was partially supported by:

• National Research, Development, and Innovation Office of Hungary under project numbers K133882 and K124351, the Ministry of Innovation and Technology and the National Research, Development and Innovation Office within the Quantum Information National Laboratory of Hungary;
• Polish National Science Center under grant agreements number 2019/33/B/ST6/0201 and 2023/07/X/ST6/00396.