# Questions tagged [scheduling]

For questions about methods that assign resources to work requests (e.g. processor time to tasks) usually minimizing some cost measure (e.g. makespan).

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127 views

### Python "Coffee Shop Scheduling Problem" - Scheduling Lunches/Breaks

I'm working on an employee scheduling program in python. Having never done this before, I've been researching different libraries that can be used to accomplish the task. Unfortunately, none of the ...
41 views

### How to model a cumulative resource constraint with same family condition?

Assume that we have 3 tasks to schedule : $x_{a1}, x_{a2}, x_{b3}$. They all use the same cumulative resource : $r_1$. Each activity increases $r_1$ by $1$ at it starts time and decreases $r_1$ by $1$ ...
73 views

### Need help with writing short proof related to Critical-Path-Method in scheduling with variable activity duration

stackexchange community, I am currently working in the area of operations research / scheduling and am attempting to write a short proof. We are working with a directed acyclic graph of activities (...
70 views

### why in coding constraints you don't get the right answer?

From "A new unrelated parallel machine scheduling problem with tool changes to minimize the total energy consumption" Zhang et al. 2020 paper. A scheduling problem that schedules $n$ jobs on ...
177 views

### How do constraints become redundant in a Big-M conjunction?

The following Big-M conjunction appears on page 14:3 of The Path&Cycle Formulation for the Hotspot Problem in Air Traffic Management: \begin{align*} \text{(i)} \quad t_{(g, \; s)} - t_{(f, \; s+...
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### How to model a non-overlap constraint between 2 groups of tasks?

Let $T$ be a set of tasks. Each task $t \in T$ has a duration $d_t$. Let $T_1 \subset T$ and $T_2 \subset T$ such as $T_1 \cap T_2 = \emptyset$ How can I model the following constraint : all tasks ...
161 views

### How to merge tasks or do batching in a quality control lab

Background information: In the Quality Control labs of pharmaceutical companies, analysts inspect products or raw materials in the units of ‘batches’ (which is essential a physical sample of bill, ...
329 views

### How to include material flow in job shop scheduling problem (as constraint?)?

I am reading about https://en.wikipedia.org/wiki/Job-shop_scheduling and https://en.wikipedia.org/wiki/Optimal_job_scheduling. Such scheduling is possible if we know the number (amount) of operations (...
314 views

### Minimizing cost of transportation and storage of items

I am looking for an optimization algorithm to minimize the cost of transportation and storage cost in warehouse. Let's assume the following table gives us the weekly forecast of Demand. ...
185 views

### How to cope with the rigidity of solutions?

Consider the following problem of Technician Routing and Scheduling Problem. We have: A set of customers where each customer needs the intervention of a technician to do some job. Each customer has a ...
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### vehicle routing optimization, Big M method of reformulation of constraints

Please excuse me for the long question, if I dont prrovide this info. my post gets removed! The following optimization problem is called Mixed-Integer Quadratically Constrained Programming (MIQCP) ...
562 views

### What is the state-of-art (in industry and academy) of this scheduling + routing problem?

I have a startup idea and I am coming from a CS background. The startup tries to solve the following problem. A company having a set of employees that needs to visit several "customers" each ...
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### Constant-factor approximation algorithms for max-min number partitioning

In the k-way number partitioning problem, the input is a set of numbers and the goal is to partition them into $k$ parts in an optimal way. The most well-studied optimization objective is to minimize ...
99 views

### Harvest planning problem

I need to model the following problem: For a planning horizon of $P$ equal periods, one has $N$ harvesting locations and $K$ contractors who can harvest at those locations ($K < N$). Each ...
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### What are (some of) the best resources for shift scheduling/rostering?

Shift scheduling/rostering is obviously very widely researched, with tons of papers around it. I found the review papers by Van den Bergh et al.  and Ernst et al. , but am looking for something ...
97 views

### Adding sequence constraints to the assignment problem- Python

This is an online assignment problem and yet can be considered as an assignment problem with a sequence. Assume that workers are coming into the system sequentially and I want to assign a task to them ...
159 views

### What strategies to use for Scheduling of Connected Sequences?

I'm given a problem in which I need to schedule multiple sequences. The goal is to minimize the makespan. I'm allowed to elongate all tasks, but I cannot reduce their width nor disconnect any of the ...
97 views

### A specific case of a resource constrained project scheduling problem with partially renewable resources (RCPSP/$\pi$) - OR-Tools

I've been trying solve a specific case of the resource constrained project scheduling problem with partially renewable resources (RCPSP/$\pi$ in the literature e.g. this paper). These resources are ...
112 views

### Scheduling of planned orders while respecting certain stock levels

I am searching for the academic name of the problem of computing a valid schedule for planned order. More precisely, The problem consists of: list of orders O, available vehicle per day K, and the ...
80 views

### Formulate a constraint set to identify the number of overlapping operations

Let assume we have operation $r \in R$, machine $n \in N$ and day $t \in T$. $S_{r}$ is the service duration of operation $r$. Note that $S_{r}$ can be defined based on time slot (e.g., $S_{1}$ can be ...
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### How to use gurobi to plan production and minimize the times of changeovers

Suppose we have two lines: L1 and L2. Suppose we have 4 product types: A1, ...
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### Resource scheduling problem with synchronization constraints: Weak LP relaxation

I have a resource assignment/scheduling problem which involves assigning jobs to $m$ workers. There are 2 sets of different jobs, $J^1$ and $J^2$, and a set of periods $T$. Let $d_{jt}$ be the number ...
101 views

### Multiple Depot/Crew Office Bus Driver Scheduling Modelling

I'm working on Bus Driver Schedule with multiple add-on constraints that are complex and hence trying to figure out how this can be achieved. Reference of Bus Driver Scheduling using OR-Tools:- https:/...
67 views

### Maximizing the minimum machine completion time

There are $n$ jobs with different processing times, and they should be scheduled on $m$ identical machines such that the smallest completion time is as large as possible. This problem is NP-hard even ...
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### multiple cranes scheduling optimization [closed]

So i'm working on my school project and The problem is described as follow: we have 31 baths and 4 cranes '1 axis of movement'. figure 1: a crane imageimagen_2021-06-01_120450.png figure 2: baths ...
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### How would I model the following problem concerning customer service via FCFS vs Appointment Scheduling

I'm unfamiliar with OR, and would like to get some advice on how to "think" about this scenario: I work for an organization that primarily has store fronts. Customer's arrive throughout the ...
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### What are the flow based formulations?

What are the flow-based formulations? For what optimization problems are they applied, and in which form? Which are the specificities of such a formulation? Also, the same question for the time staged ...
105 views

### Production planning for a video game economy

I'm a software developer who likes to play a video game that has a complex economy. I realized that the type of problem I'm trying to solve mimics real life operations research problems, and I am ...
50 views

### Heuristic to compute upper bound for the simple assembly line balancing problem type 2?

I am currently working on SALBP-2 described as: Given the number m of assembly stations, minimize the cicle time c. I have done a bit of research and found the following approach to solve it: The ...