Linear Algebra Terminology Flashcards

(36 cards)

1
Q

How do you say:

R or R^1

A

The real number line

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2
Q

How do you say:

R^n

A

The n-dimensional vector space

or

The set of ordered n-tuples of real numbers.

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3
Q

How do you say:

R^+

A

The nonnegative reals

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4
Q

How do you say:

Z

A

The set of integers

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5
Q

How do you say:

Z^+

A

The set of nonnegative integers

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6
Q

How do you say:

Z^n

A

The set of ordered n-tuples of integers

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7
Q

How do you say:

S = {a, b, c, d}

A

S is a set of elements a, b, c, d.

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8
Q

How do you say:

S = {x: P(x)}

A

S is the set defined to contain all elements x for which a condition P is true.

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9
Q

How do you say:

|S|

A

The size of set S

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10
Q

How do you say:

f: S –> T

A

A mapping f from set S to set T

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11
Q

How do you say:

2^s

A

The set of all subsets of S

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12
Q

How do you say:

A = [a_ij]

A
Matrix A (with dimensions mxn)
With element a_ij in Row i and Column j.
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13
Q

How do you say:

a_i

A

The n-vector consisting of the ith row of A

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14
Q

How do you say:

A_j

A

The m-vector which is the jth column of A

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15
Q

All vectors x are…

A

Column vectors

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16
Q

All vectors x’ are…

17
Q

How do you say:

det (A)

A

The determinant of A (which must be a square matrix)

18
Q

What is a multigraph?

A

Graphs with repeated edges. (Two vertices share more than one edge.)

19
Q

What is a directed graph? Or a digraph?

A

A graph with directions assigned to its edges.
D = (V, A)
V is the vertices
A is the arcs, ordered pairs of vertices.

20
Q

What is the degree of a vertex?

A

The number of edges incident upon that vertex.

Aka, number of edges it has

21
Q

What is a walk?

A

A sequence of vertices/nodes, 1, 2, 3, 4
Where 1 has an edge to 2,
2 has an edge to 3,
3 has an edge to 4

22
Q

What is a path?

A

A closed walk, where the first vertex connects to the last vertex of the walk.

23
Q

What is a circuit or cycle?

A

A path with no repeated vertices

24
Q

How do you calculate the length of a path?

A

If it goes from v_1 to v_k, it’s k-1

25
What is the indegree of a vertex on a digraph?
The number of arcs that go toward that vertex.
26
What is the out degree of a vertex in a digraph?
The number or arcs that go away from that vertex.
27
How do you denote a bipartite graph?
B = (V, U, E) | V and U are the two partitions of the graph, and E are the edges.
28
What does it mean if a graph is connected?
If there is a path between any two nodes in it
29
What is a tree?
A connected graph with no cycles.
30
What is a weighted graph?
A graph G= (V, E) Together with a function w: E --> Z The weights can also be called c for costs, d for distances.
31
How do we denote an edge?
[u, v]
32
How do we denote the weight of an edge?
w[u, v] or w_uv
33
What is rank in a matrix?
The dimension of the column or row space.
34
What is "full rank" in a matrix?
A matrix is said to have full rank if its rank equals the largest possible for a matrix of the same dimensions, which is the lesser of the number of rows and columns.
35
What does linear independence mean?
No vector in the set can be written as a linear combination of the others
36
What does it mean to "make a basis of matrix A"
A basis is formed through all the vectors that are linearly independent within A.