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CS173 Examlet 1 (Self-Study)
UIUC CS173 Proficiency Exam
34
Computer Science
Undergraduate 1
06/03/2018

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Cards

Term
set Z
Definition
integers {..,-1,0,1,....}
Term
Rewrite
[image]
Definition
[image]
Term
Rewrite:
[image]
Definition
[image]
Term
[image]

Rewrite
Definition
[image]
Term
set N
Definition
Natural numbers

INCLUDES 0

{0, 1, 2, 3,...}
Term
Z+ set
Definition
positive integers

{1, 2, 3, ...}
Term
set R
Definition
real numbers - both rational and irrational
Term
set Q
Definition
rational numbers (fraction that involves two integers - ex 4/3)
Term
set C
Definition
complex numbers
Term
Floor function
Definition
⌊ x ⌋
Rounds DOWN function
floor(-3.75) = -4
floor (3.75) = 3
Term
Ceiling function
Definition
⌈ x ⌉

Rounds UP function
ceiling(-3.75) = -3
ceiling(3.75) = 4
Term
Notation for set membership, and not being in set membership
Definition
Use
x ∈ Z for x is an element of Z
Cross out ∈ for not an element - similar to not equals to.
Term
Proposition definition
Definition
statement that is either true or false (but never both)

example: 2 < 15

Cannot contain variables (ex: x < 3)
Term
truth table example for p ∧ q
Definition
[image]
Term
¬p is short for...?
Definition
"not p"

Example: Urbana is not in Illinois
Term
p ∧ q
Definition
p and q
Term
p ∨ q
Definition
p or q
Term
p ⊕ q
Definition
True if only ONE is true.

See table:

[image]
Term
p → q truth table
Definition
p implies q

[image]
Term
Converse of p → q
Definition
q → p
Term
p implies q and conversely
Definition
q ↔ p
Term
contrapositive
Definition
negate both p and q, swap their roles

p → q
¬q → ¬p
Term
• If it’s below zero, my car won’t start.


Converse and contrapositive this
Definition
• converse: If my car won’t start, it’s below zero
• contrapositive: If my car will start, then it’s not below zero.
Term
q → p truth table
Definition
[image]
Term
q ↔ p truth table
Definition
[image]
Term
¬p ∨ q is equivalent to ____
Definition
p → q
Term
Logical Equivalence Symbol
Definition


Give the same truth table/output
Term
De Morgan’s Laws
Definition
¬(p ∧ q) ≡ ¬p ∨ ¬q

¬(p ∨ q) ≡ ¬p ∧ ¬q

¬(¬p) ≡ p

Distributing in ¬
Term
p ∨ (q ∧ r) ≡

p ∧ (q ∨ r) ≡
Definition
1. (p ∨ q) ∧ (p ∨ r)

2. (p ∧ q) ∨ (p ∧ r)
Term
¬(p → q) is
Definition
p ∧ ¬q
Term
Negating propositions
Definition
¬() around whole statement
Term
predicate
Definition
Statement that can be true or false
Term
Quantifier (English)
Definition
Expresses a range of values in a domain that make something true

Example in english: “some”,
“a couple”, “a few”, “many”, “most.”
Term
With shorthand and english definitions:

universal quantifier

existential quantifier

unique existence quantifier

How to combine quantifiers?
Definition
universal - "for all" - ∀

existential - "there exists" - ∃

unique existence - "there is a unique" - ∃!

Combine with a comma.
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