How this statement should be written?

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If I have a theorem/conjecture of the form "Let $n$ be an [object with some properties], then $P(n)$", how would it be written in logic ? So I have 2 variants:

1)$forall n in A, P(n)$.

2)$(nin A)to(P(n))$.

(By $A$ I mean a set of all such objects with some property).

So is one of my variants right ? Or it should be written in some other form ?







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  • So it would be kind of equivalent ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:01










  • @MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:04











  • @MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:22










  • In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
    – Clive Newstead
    Aug 2 at 14:26















up vote
0
down vote

favorite












If I have a theorem/conjecture of the form "Let $n$ be an [object with some properties], then $P(n)$", how would it be written in logic ? So I have 2 variants:

1)$forall n in A, P(n)$.

2)$(nin A)to(P(n))$.

(By $A$ I mean a set of all such objects with some property).

So is one of my variants right ? Or it should be written in some other form ?







share|cite|improve this question





















  • So it would be kind of equivalent ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:01










  • @MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:04











  • @MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:22










  • In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
    – Clive Newstead
    Aug 2 at 14:26













up vote
0
down vote

favorite









up vote
0
down vote

favorite











If I have a theorem/conjecture of the form "Let $n$ be an [object with some properties], then $P(n)$", how would it be written in logic ? So I have 2 variants:

1)$forall n in A, P(n)$.

2)$(nin A)to(P(n))$.

(By $A$ I mean a set of all such objects with some property).

So is one of my variants right ? Or it should be written in some other form ?







share|cite|improve this question













If I have a theorem/conjecture of the form "Let $n$ be an [object with some properties], then $P(n)$", how would it be written in logic ? So I have 2 variants:

1)$forall n in A, P(n)$.

2)$(nin A)to(P(n))$.

(By $A$ I mean a set of all such objects with some property).

So is one of my variants right ? Or it should be written in some other form ?









share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Aug 2 at 10:58









Bram28

54.5k33880




54.5k33880









asked Aug 2 at 9:55









Юрій Ярош

979412




979412











  • So it would be kind of equivalent ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:01










  • @MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:04











  • @MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:22










  • In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
    – Clive Newstead
    Aug 2 at 14:26

















  • So it would be kind of equivalent ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:01










  • @MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:04











  • @MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
    – Ð®Ñ€Ñ–й Ярош
    Aug 2 at 10:22










  • In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
    – Clive Newstead
    Aug 2 at 14:26
















So it would be kind of equivalent ?
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:01




So it would be kind of equivalent ?
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:01












@MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:04





@MauroALLEGRANZA No I meant,are variants I have written equivalent ?Because in my second variant I have no quantifiers, or we can transform second variant using universal generalization ?
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:04













@MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:22




@MauroALLEGRANZA Yeah, now I realized that the second statement can be true some $n$ and false for the others, so I need "for all" claim anyway, thanks for explaining.
– Ð®Ñ€Ñ–й Ярош
Aug 2 at 10:22












In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
– Clive Newstead
Aug 2 at 14:26





In so-called 'Agda notation' for dependent type theory, the notation $(n in A) to P(n)$ refers to the dependent product type $prod_n in A P(n)$, which corresponds with the proposition $forall n in A,,P(n)$ under the Curry-Howard correspondence. I'm leaving this as a comment rather than an answer because it would not be considered correct notation in mainstream mathematics.
– Clive Newstead
Aug 2 at 14:26











1 Answer
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$(nin A)to P(n)$ is a good start, but you need something to express the idea that you want this to be true for all $n$. So you should write
$$ forall n : bigl[ nin A to P(n) bigr] $$



This is what "$forall nin A. P(n)$" (with variations in punctuation that don't carry any meaning) is usually considered to be an abbreviation for in formal logic.






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    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    4
    down vote



    accepted










    $(nin A)to P(n)$ is a good start, but you need something to express the idea that you want this to be true for all $n$. So you should write
    $$ forall n : bigl[ nin A to P(n) bigr] $$



    This is what "$forall nin A. P(n)$" (with variations in punctuation that don't carry any meaning) is usually considered to be an abbreviation for in formal logic.






    share|cite|improve this answer



























      up vote
      4
      down vote



      accepted










      $(nin A)to P(n)$ is a good start, but you need something to express the idea that you want this to be true for all $n$. So you should write
      $$ forall n : bigl[ nin A to P(n) bigr] $$



      This is what "$forall nin A. P(n)$" (with variations in punctuation that don't carry any meaning) is usually considered to be an abbreviation for in formal logic.






      share|cite|improve this answer

























        up vote
        4
        down vote



        accepted







        up vote
        4
        down vote



        accepted






        $(nin A)to P(n)$ is a good start, but you need something to express the idea that you want this to be true for all $n$. So you should write
        $$ forall n : bigl[ nin A to P(n) bigr] $$



        This is what "$forall nin A. P(n)$" (with variations in punctuation that don't carry any meaning) is usually considered to be an abbreviation for in formal logic.






        share|cite|improve this answer















        $(nin A)to P(n)$ is a good start, but you need something to express the idea that you want this to be true for all $n$. So you should write
        $$ forall n : bigl[ nin A to P(n) bigr] $$



        This is what "$forall nin A. P(n)$" (with variations in punctuation that don't carry any meaning) is usually considered to be an abbreviation for in formal logic.







        share|cite|improve this answer















        share|cite|improve this answer



        share|cite|improve this answer








        edited Aug 2 at 14:22


























        answered Aug 2 at 11:08









        Henning Makholm

        225k16290516




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