Discrete Mathematics

---------------------------SYMBOLIC

LOGIC

51

The main point covered so far:

The symbols we have seen: {

A,

v,

---7,

H,

--,} are often called connectives because they connect two

Boolean expressions (although in the case of--,,

it's

only attached to a single Boolean expression).

1.4.3

Negations

The symbol

--,

, (pronounced "not") is like a negative sign in arithmetic. So,

if

we have p ("I own a cat"), the

--,p

(notice there are no parentheses) can be read as "Not I own a cat", or "

It

is not the case that I own a cat" (in

which case the--, could

be

read as "it is not the case that"). Both

of

these sound awkward, but the idea is to use

the original ...