Questions tagged [modelling]

Questions on how to represent real-world or non computer science problems with computer science tools.

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13 views

Fuzzy graph matching to merge disparate data models

I have 2 disparate data models and I want to identify when they are talking about conceptually similar things. All elements are constructed from the same basis set of 60+ observables. Compound ...
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7 views

What's a difference between Shape-From-Stereo and Shape-From-Motion approaches?

I am reading about different approaches for 3D facial reconstruction and can't get a difference between Shape-From-Stereo (SFS) and Shape-From-Motion (SFM) approaches.The SFS regresses a shape from ...
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3answers
95 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 ...
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1answer
136 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 ...
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26 views

Relational Database to Aggregate Data Model

Can any application currently using a relational database be rewritten to use an Aggregate Data Model, by Focusing on data modelling aspects only (ignoring other features like salability or ...
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1answer
29 views

How to model references in an ontology

I am interested in creating an ontology which will model arguments (among other things). For example, a triple in the ontology might be ...
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1answer
68 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 ...
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13 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 $\...
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1answer
184 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....
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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 ...
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533 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}\...
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62 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{...
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1answer
31 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 ...
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28 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 ...
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1answer
57 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 ...
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38 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 ...
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3answers
215 views

Formalizing self-propagating behaviour

Since reading Ken Thompson's Reflections on Trusting Trust I am trying to formalize the idea of a program which mutates its own behaviour; specifically, a program that would be self-reproducing except ...
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10 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. ...
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1answer
58 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 ...
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2answers
140 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,...
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2answers
187 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 ...
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69 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 ...
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2answers
235 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 ...
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3answers
162 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 \...
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1answer
226 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} \...
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1answer
175 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 ...
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1answer
697 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 ...
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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 - ...
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266 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 ...
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1answer
96 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 ...
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2answers
88 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 ...
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2answers
144 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 ...
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0answers
39 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} = ]...
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1answer
35 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 ...
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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 ...
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1answer
282 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 ...
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1answer
690 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.
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45 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 ...
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0answers
63 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 ...
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37 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)...
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2answers
323 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 ...
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0answers
218 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
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1answer
290 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 ...
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3answers
150 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
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1answer
98 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 ...
3
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1answer
52 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 ...
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1answer
237 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 ...
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181 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. $G$ ...
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0answers
24 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 ...
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510 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 ...