Vocab Flashcards

1
Q

Algorithm

A

A finite sequence of step-by-step instructions carried out to solve a problem

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2
Q

Trace table

A

Used to record the values of each variable as the algorithm is run

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3
Q

Pros and Cons of First Fit Bin Packing

A

Pro: Quick and easy
Con: Is unlikely to generate the optimal solution

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4
Q

Optimal Solution

A

A solution that cannot be improved upon

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5
Q

Pros and Cons of First Fit Decreasing Bin Packing

A

Pro: Easy to implement; often generates a better solution than first fit.
Con: Doesn’t guarantee an optimal solution; the list first needs to be sorted into decreasing order which makes the problem more complex.

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6
Q

Pros and Cons of Full Bin Packing

A

Pro: Usually generates the optimal solution.
Con: Difficult, especially with long lists.

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7
Q

Efficiency of an algorithm

A

A measure of the run-time of the algorithm and is normally proportional to the number of operations that need to be carried out.

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8
Q

Size of the problem

A

A measure of the complexity of a problem. In sorting algorithms, it is usually the number of elements in the list.

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9
Q

Order of an algorithm (complexity)

A

A measure of the efficiency as a function of the size of the problem.

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10
Q

Graph

A

Consists of nodes/vertices that are connected by edges/arcs

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11
Q

Subgraph

A

A subgraph of G only contains edges and vertices that belong to G

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12
Q

Directed edges

A

Edges that have a direction associated with them

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13
Q

Digraph

A

A graph that contains 1 or more directed edges

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14
Q

Weight

A

Number associated with an edge

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15
Q

Weighted graph

A

A graph which only contains edges that have numbers associated with them (weights)

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16
Q

Degree/valency

A

The number of edges that are incident on a vertex

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17
Q

Odd vertex

A

A vertex of odd degree i.e. an odd number of edges is incident on it.

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18
Q

Even vertex

A

A vertex of even degree, i.e. an even number od edges is incident on it.

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19
Q

Euler’s Handshaking Lema

A

Every finite undirected graph has an even number of vertices of odd degree.
The sum of the valencies of all the vertices of a graph is equal to twice the total number of edges.

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20
Q

Path

A

A finite sequence of edges, where the end vertex of one edge is the start vertex of the next edge and no vertex appears more than once.

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21
Q

Cycle/Circuit

A

A closed path, i.e. the end vertex of the last edge is the start vertex of the first edge.

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22
Q

Simple graph

A

Contains no loops and there is at most 1 edge connecting a pair of vertices.

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23
Q

Hamiltonian cycle

A

A cycle that passes through every vertex of a graph

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24
Q

Walk

A

A finite sequence of edges such that the end vertex of one edge is the start vertex of the next edge

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25
Q

Tour

A

A walk that visits every vertex and returns to the start vertex

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26
Q

Trail

A

A walk where no edge is visited more than once

27
Q

Loop

A

An edge that starts and finishes at the same vertex

28
Q

Connected

A

Vertices are connected if there is a path between them. A graph is connected if every vertex is connected

29
Q

Tree

A

A graph with no cycles

30
Q

Spanning tree

A

A spanning tree of G is a subgraph of G that contains all of the vertices of G and is a tree

31
Q

Complete graph

A

Every vertex is connected to every other vertex exactly once. A simple graph

32
Q

Eulerian graph

A

Every vertex has even degree

33
Q

Semi-eulerian graph

A

Exactly 2 vertices have odd degree

34
Q

Eulerian cycle

A

Cycle that contains every edge of a graph exactly once

35
Q

Planar graph

A

A graph that can be drawn in a single plane such that no edges meet each other, except at vertices to which they are both incident.

36
Q

Isomorphic

A

Two graph that have the same number of edges and the degrees of the corresponding edges are the same.

37
Q

How to check that graphs are isomorphic

A

Write down the valencies of all vertices. Check pairings of valencies. i.e. all vertices in 1 graph must be connected to vertices that have the same valencies as on the 2nd graph

38
Q

Adjacency Matrix

A

Describes the number of arcs joining the corresponding vertices. Loops = 2; 0 in leading diagonal = no loops; symmetry in leading diagonal = no directed edges

39
Q

Distance matrix

A

Every entry corresponds to the weight of each arc. If no loops, dashes down leading diagonal. Dash = no edge

40
Q

Decision Variables

A

Numbers of each of the things that can be varied

41
Q

Objective

A

Aim of the problem

42
Q

Objective function

A

The objective of a problem written as an equation using the decision variables

43
Q

Constraints

A

Prevent you from using/making an infinite number of each of the things represented by the decision variables. Each one gives rise to 1 inequality.

44
Q

Feasible solution

A

Satisfies all the constraints

45
Q

Feasible region

A

Contains all possible feasible solutions

46
Q

Optimal solution

A

A feasible solution that meets the objective. There can be multiple

47
Q

Slack variable

A

Represents the difference between the amount of the resources available and the amount used

48
Q

Basic variable

A

Variables that don’t have a value of 0

49
Q

Non-basic variables

A

Variables that have a value of 0

50
Q

Basic solution

A

Feasible solution with no profit. i.e. all variables in objective function are non-basic variables

51
Q

Surplus variable

A

Represent the difference between the minimum amount of resource available and the amount used

52
Q

Artificial variable

A

Used to ensure that surplus variables are greater than or equal to 0.

53
Q

Source node

A

Represents the start of a project

54
Q

Sink node

A

Represents the end of a project

55
Q

Event

A

Completion of 1 or more activities

56
Q

Dummy Activity

A

Has 0 duration

57
Q

When to use dummies

A

1) To represent dependency

2) Each activity must be uniquely represented in terms of events.

58
Q

Early event time

A

The earliest time of arrival at the event allowing for the completion of all preceding activities

59
Q

Forward Pass

A

Calculates the early event times

60
Q

Late event time

A

The latest time that the event can be left without extending the time needed for the project.

61
Q

Backwards pass

A

Calculates the late event times

62
Q

Critical activity

A

Has 0 float, i.e. any delay in its duration or start will delay the project’s completion by the same amount of time.

63
Q

Critical Path

A

A path from the source node to the sink node which is formed entirely of critical activities.

64
Q

Resource Levelling

A

The process of adjusting start and finish times of activities in order to take into account the constraints of the resources.