Questions tagged [modelling]
Questions on how to represent real-world or non computer science problems with computer science tools.
0
votes
0answers
35 views
How to use nested for loops for brute forcing combinations - Python [migrated]
I wish to do the following:
1) Try a variety of input combinations to search for a best result
2) Reset all arrays as they were before each loop of the code
Every variable I am working with is in an ...
1
vote
1answer
16 views
What is the difference between “information model” and “conceptual model”?
I am trying to figure out the difference between information and conceptual models. For me, both terms seem to mean be the same, but I cannot find a reference where this is established. They are never ...
0
votes
0answers
9 views
Timed Kripke structures with inequality constraints
I am having problems creating a timed Kripke structure $\mathcal{TK} = \langle S, \mathcal{T}, \rightarrow, L \rangle$ for a system that I have.
My system, a timed automaton system (time base $\...
0
votes
1answer
37 views
How to write an if then logical constraint given part of the input related to a decision variable?
I am trying to solve an assignment problem-like from a bi-objective persepctive where I have a marketplace of vendors proposing different machines with different types and specs. The goal is to select ...
0
votes
1answer
26 views
How to evaluate the learned prototypes for multivariate time-series (e.g. motion)?
Consider a method which finds prototypes for multivariate time-series (MTS) data, and is designed to find prototypes for each class of data.
For example, the {walking} class consists of some slightly ...
1
vote
0answers
275 views
Restriction for greater than constraint in linear programming
I have a model that considers real values and that uses a binary variable $x$. In this model, the following conditions should apply:
\begin{equation}
x=
\begin{cases}
0, & \text{if}\...
1
vote
1answer
27 views
What is a logical approach to developing an algorithm which can find the optimal parameters for a function which make it best fit a given data set?
Consider the highlighted columns in the following table:
Starting with 100,000 newborns, $l_{x+2}$ denotes the number of individuals in the sample still alive at age $x+2$. If we consider Makeham's ...
0
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0answers
48 views
How to model an ''affinity constraint'' in assignment problem
Working on an optimization problem formulated using the well known assignment problem. My decision variable is defined as follows :
$$\alpha _{x}^{r,u} = 1\begin{cases}
& \text{ 1 if } \mathbf{...
0
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0answers
25 views
How to define a generic evaluation metric
Given a system (S) that accepts a tuple of parameters ($\alpha, \beta, \gamma \dots$ etc). These parameters affect the performance of S in a different way. For instance, decreasing $\alpha$ would ...
1
vote
1answer
49 views
Develop a winning strategy for a game
Okay so I've been going crazy about this problem I was given. It is as follows:
Given a pile of N matches, 2 people take turns removing matches from the pile. When it is your turn you are allowed ...
4
votes
1answer
175 views
Is this problem just an application of traveling salesman? If not is it some other already “solved” problem?
Description of the problem in question:
Say I have a complete graph with positive weighted edges. 1 vertex is specified as the "end". A subset of the other vertices are designated as "start" vertices....
1
vote
0answers
30 views
DAGs and Equivalence Class of DAGs
I am learning DAGs and Equivalence Class of DAGs, I am reading the material by Prof. Campos Ibáñez here: https://www.cs.cmu.edu/afs/cs/project/jair/pub/volume18/acid03a-html/node2.html
However, I ...
1
vote
0answers
8 views
B2B integration modelling tools and standard suggestions
This question might be too broad, but I really need help with this. I am required to choose a standard or notation to model an integration between two business processes, one of which is external.
...
1
vote
1answer
43 views
How to convert two conflicting objective functions into a single objective function
I have two objective functions say f1 where I have to minimize (X+Y) and another function f2 where I have to maximize (A-B). The two functions are conflicting.
I need to convert them into a ...
3
votes
2answers
123 views
How can union-find algorithm be used with “real” data
In the beginning of the Princeton algorithms course the Dynamic connectivity problem is presented (quick-find, quick-union). Here is how it's described:
The input is a sequence of pairs of integers,...
0
votes
2answers
134 views
Modeling tiling problems as SAT problems
I read that tiling problems can be modeled as satisfiability problems (2-SAT?), but the author did not explain how. Is this true? What would be an example?
By a "tiling problem" I mean you have a ...
0
votes
0answers
58 views
Applying Ford-Fulkerson to settle a business lunch
I want to organize a business lunch with two societies $E_1$ (mine) and $E_2$. Each society is made of four people from the Executive management and 6 of the Financial Management. I want to organize ...
3
votes
3answers
143 views
Integer linear programming formulation of formula in DNF
I have multiple sets, e.g.,
$$\{1, 2\}, \{2, 3, 4\}, \{1, 4\}$$
Each variable $1, 2, 3, 4$ is binary. I need to represent the following condition without additional variables
$$(1 \land 2) \lor (2 \...
2
votes
2answers
223 views
Matching two people. One has 7% in common with the other. The other has 70% in common. What's a fair match score?
I am exploring some ideas around dating site matching, and I can do with some ideas as to which is the better solution
Senario: We have a boy and girl, the boy has completed his profile/bio ...
3
votes
1answer
180 views
Expressing a logical constraint in integer programming
Let $x$ be an integer such that $x \in [ - 10,10]$ and $b$ a binary variable. Apply integer programming to express $b = 1 \leftrightarrow x \ge3$
My work:
\begin{equation}
\begin{cases}
\...
1
vote
1answer
125 views
Set Cover and additional constraints
Consider the following bipartite graph:
Each node in red color represents a warehouse $w = \{ 1,2,3\} $. For this example we have three warehouses located at different locations. Each warehouse has a ...
2
votes
2answers
66 views
How to Determine Places, Transitions and Tokens in a Scenario when Modeling with Petri Nets?
When modeling a scenario with Petri nets how should I determine the places, transitions and tokens?
Example:
There are two exam assistants in an exam hall observing the exam. They stand in front of ...
3
votes
1answer
503 views
Linear programming formulation for the single-source shortest path problem
In this course lecture; section 5.1, single-source shortest path (SSSP) is formulated as the following linear program (LP):
\begin{align}
\max &\sum d_u \\
\text{subject to} & \\
d_v &\le ...
3
votes
0answers
255 views
The meaning of ontology in computer science
I am reading a paper and ran into this word Ontology-based, What does it really mean? I did searching about it but still ambiguous to me, can someone elaborate this ...
0
votes
1answer
44 views
How to conceptually represent attributes (characteristics) of an object in logics?
I am reading about/working on the knowledge representation using OpenCog framework http://wiki.opencog.org/w/OpenCog_Framework which essentially is special kind of probabilistic logic (s.c. PLN - ...
1
vote
1answer
76 views
Ambiguity in choosing the best ER model
I am actually little bit confused when I am reading through the text - Database system concepts by Henry F. Korth and others
I won't be able to understand one thing, which one of the following models ...
1
vote
0answers
33 views
Modelling belonging of a real variable to an interval by a boolean variable
In the context of a MILP, I have variables $x_{t} \in \mathbb{R}$ which have a lower bound $x^{min}$ and an upper bound $x^{max}$.
Let $I_{1} = [x^{min},a_{1}], I_{2} = ]a_{1}, a_{2}], ..., I_{n} = ]...
0
votes
1answer
31 views
How to simulate systems' unavailability?
I am simulating a system where the clients' unavailability is one big issue to the systems behavior.
I gathered the real system logs to analyze the unavailability of the clients in the deployment ...
6
votes
2answers
81 views
CNF form of variable assignment problem
There are n variables $x_1$, $x_2$,..., $x_n$ and each one of them takes values from 1 to k (k>= n) and all are distinct. How can I represent this in the CNF form? (I tried the trivial way of trying ...
2
votes
0answers
55 views
An alternative to the object paradigm
I've been playing around with an alternative to the standard object-oriented paradigm for modeling data, and I would like to know if there is any research or already existing systems along the same ...
1
vote
1answer
249 views
Scheduling N variable-time interdependent tasks across M workers
I have N tasks, each of them requires some time to complete. Time to complete is not the same for all tasks. Each task may depend on a number of other tasks (assume, that no dependency cycles are ...
-1
votes
1answer
539 views
Stereotype in UML
What is a Stereotype in Unified modelling language?And What are the primary class stereotypes?.I need clear explanation using diagrams or real world scenario.
0
votes
0answers
44 views
choosing right neural network architecture and input features
As a short example suppose we have a kind of pollution sensor and a jet fan in a tunnel.
Jet fan turn on/off according to the automatic scenario based on pollution sensor value.
Pollution itself ...
4
votes
2answers
119 views
Modelling a dependency of multiple transitions on data in one place
We are modeling our process using a colored Petri net. One of the limitations we have is that when multiple transitions depend on one place, only one of those transitions will fire because then the ...
1
vote
0answers
46 views
How to mitigate the hierarchical error propagation in tree-structured classification
Suppose we have a multi-class classification problem, where the number of classes $K \geq 3$
We use a tree structure of multiple SVMs to divide and conquer the problem, with one example in the figure ...
1
vote
0answers
36 views
Middle ground between model-based and model-free approaches
In the context of the reinforcement learning domain, the dichotomy between model-based (learn a model and used it to determine a controller) and model-free (learn a controller without learning a model)...
4
votes
2answers
267 views
Dynamic Shortest Path with Linear Programming
Consider a grid with $x=5$ columns, $y=5$ rows, and $T$ timesteps.
There are $N=2$ agents in this grid, which can move vertically or horizontally. The positions of each agent $x$ at timestep $t$ is ...
4
votes
0answers
174 views
Context-free grammar for DAGs?
I'm looking for a "safe" representation of DAGs. With "safe" representation I mean that it can be described by a context-free grammar. Ideally, this grammar would be suitable for a simple LR parser.
...
2
votes
1answer
246 views
Efficient formulation for binary integer linear programming
Problem:
There are two types of balls, big (B) and small (S), which need to packed into boxes. One box can contain either:
nothing, or
1 S, or
1 B, or
2 S, or
2 B, or
1 B and 2 S
We are given the ...
2
votes
1answer
88 views
How does the Weibull distribution work as fault model in wireless sensor networks?
I am a little bit confused with the concept of using the Weibull distribution or other distribution for fault model. As I understand, in simulation this distribution is often used for modelling a ...
4
votes
1answer
48 views
Finding a method to classify pixels according to how drastic their intensity change
I am looking for a method to classify pixels into three groups: (1) Pixels which does not change their intensity much in general (the slight changes may be due to noise only), (2) Pixels which change ...
5
votes
3answers
141 views
Terminology needed for the computational solution to the Rubik's Cube
I apologize if this question is out of the guidelines of this forum. If it is please let me know and I will abstain from requesting definitions and terminology.
Hello! I am currently writing a ...
2
votes
1answer
187 views
Why arrival process of packets at a switch is not a Poisson Process?
"Packet arrivals are not Poisson
.... but some events are, such as web requests and new flow arrivals"
I know since the network traffic is very bursty, they are not Poisson.
But I am unable to ...
1
vote
0answers
164 views
Integer programming for the courier (goods delivery) scheduling problem
Model: Consider an undirected, weighted, complete graph $G = (V, E = V \times V, w: E \to \mathbb{N}^{+}, r: V \to \mathbb{N}^{+}, d: V \to \mathbb{N}^{+})$. $s \in V$ is a source vertex.
$G$ ...
2
votes
0answers
23 views
A* orientation discretization
I have a space with obstacles I wish to find a path through. What I can do is discretize the space into a grid and use A* (or D* or whatever) to find a path through it. I wish to now add orientation ...
6
votes
2answers
348 views
How to impose Euclidean distance constraint in a constraint satisfaction problem without quadratic constraints?
Best reference I could find is this one. However, I could not quite understand this one since there is no numerical example.
What I am trying to achieve with one sentence
How can I answer the ...
2
votes
0answers
162 views
How to select a good window size in the Running Gaussian Average method for Selective Background Updating?
I have been studying the Selective Background Updating in Running Gaussian Average Method, as discussed in the Wikipedia (the Variant method). The details of the algorithm, as I understand, is as ...
2
votes
1answer
301 views
Selective Background Updating in Running Gaussian Average Method for Background Subtraction
I am studying the Running Gaussian Average Method for background subtraction. One alternative, as described in Wikipedia, also known as Selective Background Updating, is to only update the ...
0
votes
1answer
421 views
Please explain linear programming as seen for this load balancing problem
I have at hand a linear program related to load balancing. However I have no idea what this is and wikipedia gives me something too simplified/abstract to be useful.
I wonder if someone can explain ...
1
vote
1answer
152 views
What is the reason of using Gaussian model for Background Modeling?
I am a new learner to Background Subtraction (Background Modeling) and I am reading a few previous works on how it is performed. Starting with Wikipedia (by searching "Background Subtraction"), I ...
