Silly question need a quick answer

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The discussion revolves around the interpretation of a mathematical notation involving parentheses and the variable "n." Participants clarify that the notation refers to the binomial coefficient, specifically "n choose 2," which represents the number of ways to choose 2 items from a set of n items. The original poster expresses gratitude for the clarification. The conversation highlights the importance of understanding mathematical symbols in combinatorics. Overall, the exchange emphasizes the significance of clear communication in discussing mathematical concepts.
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How do you read this, what does this form stand for? I can't type it here but i hope i can explain it. Parentheses n 2 below the n close parentheses.
 
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I assume you mean the http://en.wikipedia.org/wiki/Binomial_coefficient" .

You read it: "n choose 2".
 
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Yes that's what i was looking for thank you.
 
I'm taking a look at intuitionistic propositional logic (IPL). Basically it exclude Double Negation Elimination (DNE) from the set of axiom schemas replacing it with Ex falso quodlibet: ⊥ → p for any proposition p (including both atomic and composite propositions). In IPL, for instance, the Law of Excluded Middle (LEM) p ∨ ¬p is no longer a theorem. My question: aside from the logic formal perspective, is IPL supposed to model/address some specific "kind of world" ? Thanks.
I was reading a Bachelor thesis on Peano Arithmetic (PA). PA has the following axioms (not including the induction schema): $$\begin{align} & (A1) ~~~~ \forall x \neg (x + 1 = 0) \nonumber \\ & (A2) ~~~~ \forall xy (x + 1 =y + 1 \to x = y) \nonumber \\ & (A3) ~~~~ \forall x (x + 0 = x) \nonumber \\ & (A4) ~~~~ \forall xy (x + (y +1) = (x + y ) + 1) \nonumber \\ & (A5) ~~~~ \forall x (x \cdot 0 = 0) \nonumber \\ & (A6) ~~~~ \forall xy (x \cdot (y + 1) = (x \cdot y) + x) \nonumber...
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