sciforums SciForums.com : Science : Physics & Math
Logical Symbols
Encyclopedia Register FAQ Members List Social Groups Ban List Calendar Search Today's Posts Mark Forums Read
Reply
 
Thread Tools Rate Thread
CheskiChips's Avatar CheskiChips
חזאי (2,797 posts)
Old 11-04-09, 02:37 AM
 #1
Reply With Quote   CheskiChips is offline
Can someone explain the difference (Logically) of the following symbol set.







¬

For example...what's the difference between the following statements...

A¬B and A→!B


Is it simple application differences?

and...

Is there just a symbol symbol for "If"
As in...
(IF) A^BvC --> D
James R's Avatar James R
Just this guy, you know? (18,948 posts)
Old 11-04-09, 04:04 AM
 #2
Reply With Quote   James R is online now
The fourth symbol is not a symbol of equivalence, as I understand it - it is the NOT symbol for logical negation. Another symbol for NOT is !, so ¬A and !A both mean "NOT A".

The other three symbols are symbols of equivalence, which is the same as "if and only if".

There's no need for a symbol for "if", since a statement like

A -> B

already means "if A is true then B is true".
CheskiChips's Avatar CheskiChips
חזאי (2,797 posts)
Old 11-04-09, 04:48 AM
 #3
Reply With Quote   CheskiChips is offline
Right and thanks, my post was poorly divided into sections.

Regarding the first 3, is there no difference in functionality or better said...is there an instance where symbol 1 in a certain context is more valid and/or conventionally accepted than symbol 2?
temur's Avatar temur
man of no words (1,083 posts)
Old 11-04-09, 07:14 AM
 #4
Reply With Quote   temur is offline
I don't know of the third symbol. In typical mathematics I would say the first one is used to denote equivalence between sentences, and the second one is to denote identity between functions.
rpenner
Fully Wired (569 posts)
Old 11-04-09, 11:54 AM
 #5
Reply With Quote   rpenner is online now
All language is contextual -- meaning various authors can define the symbols to mean something different than any reference tells you.

But, I have see the first being used as a true equivalences between sentences, and the third as a logical connective within a sentence.

So would be a theorem (or axiom) connecting two sentences, while would be a single sentence, of the form "if just one of A = B and C = D is true, then (A - B)(C-D) = 0." With a theorem (or axiom) in a single sentence, you need to construct a syllogism (using something like modus pones) to apply it.
NMSquirrel's Avatar NMSquirrel
God is not inside the box.. (453 posts)
Old 11-04-09, 09:03 PM
 #6
Reply With Quote   NMSquirrel is offline
we need more math geeks in the world..keep it up guys..lol

you lost me at modus pones...
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sixty Symbols Robin Hood Astronomy, Exobiology, & Cosmology 7 05-18-09 10:52 PM
Logical fallacy "Appeal to authority" Michael Religion 151 03-13-09 04:05 AM
The Logical Positivism Movement Tnerb General Philosophy 2 01-12-09 02:02 AM
Logical Positivism, Jonathon Swift, and Neurosis coberst General Philosophy 0 04-12-08 05:14 PM
Logical Positivism coberst General Philosophy 0 05-09-07 07:27 AM

All times are GMT -5. The time now is 03:03 AM.