VGLA sets, Matrices and Vectors Flashcards
set
a collection of things
|A| (Sets)
the order of A (how many elements A has)
Do not count repeated elements twice
[]
includes that last element
()
excludes that last element
empty dot
excludes the last value
full dot
includes the last value
A\B
(A-B)
those elements which are in A but not in B
Cartesian Product words
The collection of ordered pairs obtained by the product of two non empty sets.
IT RETURNS A SET FROM MULTIPLE SETS.
U
union (inclusive or)
or the universal set
∩
intersection (and)
a set of the empty set is not…
the empty set
exclusive or
it can either be one or the other but not both
inclusive or
it can be one or the other or both
set operations are commutative
the order of operations does not matter (except for A\B != B\A)
set operations are Associative
placement of brackets does not matter
AUB)UC = AU(BUC
set operations are distrubutive
AU(B∩C) = (AUB)∩(AUC) A∩(BUC) = (A∩B)U(A∩C)
A’
complement of A (everything but the elements in A)
De Morgans Law
(AUB)' = A' ∩ B' (A∩B)' = A' U B'
Cartesian Product
AxB = {(a,b): aЄA, bЄB}
induction steps
- show true when n=1
- assume true when n=k
- show true when n=k+1
ℕ
natural numbers, positive integers
Z
integers
Q
rational numbers
What makes equations linear?
no products + no powers
system of linear equations
a collection of equations that are related, not every equation has to have all the unknowns.
When does a system of linear equations have a solution (c1, c2, c3…)
whenever the values x1 = c1, x2 = c2 etc simultaneously satisfy all the equations
possible solutions for systems of equations:
- no solutions
- a unique solution
- infinitely many solutions
homogeneous system
The constants (RHS) are all equal to 0
solution of a homogeneous system
(0,0,0) (trivial solution, not often of interest)
matrix
and array of numbers
mxn order matrix
m rows and n columns
aij
access the element of a matrix where i is the row and j is the column
two matrices are equal iff
- same order
- every element is equal
sub matrix
part of a bigger matrix (not equal to the original matrix)
Rule for matrix addition
matrices must be the same size
zero matrix
a matrix where all the elements are 0
properties of matrix addition: closed
if you add two matrices of the same order the output has the same order
properties of matrix addition: Associativity
the placement of brackets doesn’t matter
properties of matrix addition: Identity
A + the zero matrix = A
properties of matrix addition: Inverse
A + its inverse = the zero matrix
properties of matrix addition: commutativity
order of addition doesn’t matter
multiplying a mxn matrix by a nxp matrix
a matrix of size mxp
properties of matrix multiplication:closed
if you take any square matrices the result will be in the original subset
properties of matrix multiplication: Associativity
placement of brackets doesn’t matter
properties of matrix multiplication: Identity
IA = AI = A
properties of matrix multiplication: Inverse
not possible
properties of matrix multiplication: Commutative
A.B != B.A
diagonal matrix
aij = 0 for i!=j
Upper triangular matrix
numbers in top triangle.
aij = 0 where i>j
Lower triangular matrix
numbers in bottom triangle
aij = o where i