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Language, Proof, and Logic
Chapter 1: Atomic Sentences
19
Philosophy
Undergraduate 3
12/27/2011

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Term
atomic sentences consist of what?
Definition
Names and predicates (predicates state what the subject does) Ex: Max SAW Claire
Term
FOL stands for what?
Definition
First order logic
Term
Using FOL, interpret the meaning of: Cube(b), Larger(c,f), Between(b,c,d)
Definition
b is a cube,
c is larger than f,
b is between c and d.
Term
Define individual constant
Definition
Symbols used to refer to a fixed object. Ex: A persons name
Term
Names in FOL are represented by what letters of the alphabet?
Definition
Letters a - f (and subscript name1 and name2)
Term
Three things to remember about individual constants:
Definition
Every individual constant must name an object that actually exists

No individual constant can name more than one object

An object can have more than one name, or no name at all
Term
Define predicate symbols (also known as relational symbols) used in FOL
Definition
symbols used to express some property of an object or a relationship between objects Ex: Small(max) - meaning Max is small (where small is the predicates symbol)
Term
Logical subjects: arguments of the predicate
Definition
Ex: Max likes Claire (Max & Claire are logical subjects)
("likes" is the predicate referencing the subject)
Term
arity of a predicate
Definition
the number of arguments referenced by the predicate
Ex arity of 1: Home(max)
Ex arity of 2: Smaller(c,b)
Ex arity of 3: Between(b,a,c)
Term
determinate property in FOL means what?
Definition
that there is a precise interpretation. unlike in normal English where terms can be vague Ex: at what age do you stop being young.
Term
infix vs prefix
Definition
Infix: the arguments are placed on either side of the predicate Ex: a=b

Prefix: the arguments are after the predicate Ex: Smaller(a,b)
Term
Function symbols: (also known as terms)
Definition
noun phrases used to form complex subjects (very similar to names). Ex: Max's father likes tennis - "Max's father" is the function symbol
Term
Define Terms:
Definition
noun phrases that refer to an individuals. Ex: Max's father or Father(max)
(works just like individual constants/names do)
Term
complex terms:
Definition
Ex: Taller(father(max),max)
is
Max's father is taller than Max
Term
FOL of set theory:
Definition
Only has two types of predicates (things that link subjects):

The identity symbol: "=" and the membership symbol: "∈"
Term
Set theory: membership
Definition
"∈" Symbold:
Ex: a = 2 and b = {2,4,6} So "a" is a member of the set "b"

So: a ∈ a is False
a ∈ b is True
b ∈ a is False
b ∈ b is False
Term
FOL of arithmetic:
Definition
Uses: 0,1
(=,<) for predicates
(+,x) for functions
Term
Inductive definitions (FOL Arithmetic)
Definition
The names 0,1 are terms

If t1 , t2 are terms, then the expression (t1+t2) and (t1xt2) are also terms
Term
FOL Arithmetic atomic sentences
Definition
One times One is less than one plus one is the same as

(1x1)<(1+1)
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