Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

• Index
•  » Exercises

## #1 2011-07-07 06:21:31

dangermulan1988
Member

Offline

Last edited by iwan_ccie (2011-07-11 23:38:34)

## #2 2011-07-07 07:49:12

anonimnystefy
Real Member

Offline

hi iwan_ccie

third one is a tautology

fourth one is contingent

and the fifth one is also contingent.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

## #3 2011-07-07 07:57:16

anonimnystefy
Real Member

Offline

hi iwan_ccie

there are several ways to determine if a proposition is a tautology or a contradiction.
the easiest one is to make a table,make columns for all the boolean variables and then plug them into the equation and if the equation is always true then it is a tautology,and if it is always incorrect than it is a contradiction.
the other one works only when you have to prove that it is a tautology.it is called reductio ad absurdum.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

dangermulan1988
Member

Offline