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Questions tagged [modelling]

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

96 questions
29
votes
4 answers

How to determine likely connections in a social network?

I am curious in determining an approach to tackling a "suggested friends" algorithm. Facebook has a feature in which it will recommended individuals to you which it thinks you may be acquainted with. These users normally (excluding the edge cases in…
phwd
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24
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8 answers

What randomness really is

I'm a Computer Science student and am currently enrolled in System Simulation & Modelling course. It involves dealing with everyday systems around us and simulating them in different scenarios by generating random numbers in different distributional…
MAK7
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23
votes
1 answer

Clustering of Songs (The Joe Walsh Problem)

The Eagles are a rock supergroup from the 70s and 80s, responsible for such classics as Hotel California. They have two quite distinctive sounds, one where guitarist Joe Walsh is present (for example, in Life in the Fast Lane) and one where he is…
Dave Clarke
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17
votes
4 answers

Efficient encoding of sudoku puzzles

Specifying any arbitrary 9x9 grid requires giving the position and value of each square. A naïve encoding for this might give 81 (x, y, value) triplets, requiring 4 bits for each x, y, and value (1-9 = 9 values = 4 bits) for a total of 81x4x3 = 972…
Kevin
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15
votes
4 answers

How to devise an algorithm that suggests feasible cooking recipes?

I once had a veteran in my course that created an algorithm that would suggest cooking recipes. At first, all sort of crazy recipes would come out. Then, she would train the cooking algorithm with real recipes and eventually it would suggest very…
Oeufcoque Penteano
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11
votes
2 answers

CCS process for a drink dispenser with two different prices

A drink dispenser requires the user to insert a coin ($\bar c$), then press one of three buttons: $\bar d_{\text{tea}}$ requests a cup of tea $e_{\text{tea}}$, ditto for coffee, and $\bar r$ requests a refund (i.e. the machine gives back the coin:…
Gilles 'SO- stop being evil'
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10
votes
2 answers

Peer grading design - choosing a graph, to get accurate rankings/ratings

Background. I am writing some code for semi-automated grading, using peer grading as part of the grading process. Students are given pairs of essays at a time, and the students have a slider to choose which is better and how much better it is. …
ismail
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7
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2 answers

Building probability distribution functions from observation

There are N players and M objects, each of the objects has a value. Each player has a strategy in choosing an object. Each round a player will choose an object, many players can choose the same object. However the value of each object is divided…
Mike G
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7
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2 answers

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 all assignments and then checking if they are…
Gilfoyle
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7
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2 answers

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 following question by using constraint programming: The…
padawan
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7
votes
1 answer

Efficient queriable data structure to represent a screen with windows on it

(this is related to my other question, see here) Imagine a screen, with 3 windows on it: I'd like to find an efficient data structure to represent this, while supporting these actions: return a list of coordinates where a given window can be…
daniel.jackson
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6
votes
1 answer

How to represent the interests of a Facebook user

I'm trying to figure out a way I could represent a Facebook user as a vector. I decided to go with stacking the different attributes/parameters of the user into one big vector (i.e. age is a vector of size 100, where 100 is the maximum age you can…
mabounassif
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6
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1 answer

How to score a given arrangement of windows on a screen to produce good layouts

(this is related to my other question, see here) I would like to write a function that scores a given arrangement of windows on a screen. The purpose of this function is to determine whether a particular layout is good and by going over other…
daniel.jackson
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5
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3 answers

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 program to find the shortest path solution in a…
TestingTuring
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5
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3 answers

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 that it would reproduce itself with a mutation.…
Francesco Gramano
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