Quantifier difference












0














What s the difference between $ n in Z implies n(n+1) =2k $ such that $k in Z$ and $ forall n in Z implies n(n+1) =2k $ such that $k in Z$



Is this true:
$ (n in Z implies n(n+1) =2k $ such that $k in Z) implies forall n in Z; n(n+1) =2k $ such that$ k in Z$










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  • None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
    – Lord Shark the Unknown
    Nov 19 '18 at 7:15










  • / means such that in my case
    – J.Moh
    Nov 19 '18 at 8:19










  • Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:32










  • The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:33












  • Rewritten in an unambiguous way
    – J.Moh
    Nov 19 '18 at 10:47
















0














What s the difference between $ n in Z implies n(n+1) =2k $ such that $k in Z$ and $ forall n in Z implies n(n+1) =2k $ such that $k in Z$



Is this true:
$ (n in Z implies n(n+1) =2k $ such that $k in Z) implies forall n in Z; n(n+1) =2k $ such that$ k in Z$










share|cite|improve this question
























  • None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
    – Lord Shark the Unknown
    Nov 19 '18 at 7:15










  • / means such that in my case
    – J.Moh
    Nov 19 '18 at 8:19










  • Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:32










  • The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:33












  • Rewritten in an unambiguous way
    – J.Moh
    Nov 19 '18 at 10:47














0












0








0







What s the difference between $ n in Z implies n(n+1) =2k $ such that $k in Z$ and $ forall n in Z implies n(n+1) =2k $ such that $k in Z$



Is this true:
$ (n in Z implies n(n+1) =2k $ such that $k in Z) implies forall n in Z; n(n+1) =2k $ such that$ k in Z$










share|cite|improve this question















What s the difference between $ n in Z implies n(n+1) =2k $ such that $k in Z$ and $ forall n in Z implies n(n+1) =2k $ such that $k in Z$



Is this true:
$ (n in Z implies n(n+1) =2k $ such that $k in Z) implies forall n in Z; n(n+1) =2k $ such that$ k in Z$







quantifiers






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 19 '18 at 10:45

























asked Nov 19 '18 at 6:45









J.Moh

395




395












  • None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
    – Lord Shark the Unknown
    Nov 19 '18 at 7:15










  • / means such that in my case
    – J.Moh
    Nov 19 '18 at 8:19










  • Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:32










  • The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:33












  • Rewritten in an unambiguous way
    – J.Moh
    Nov 19 '18 at 10:47


















  • None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
    – Lord Shark the Unknown
    Nov 19 '18 at 7:15










  • / means such that in my case
    – J.Moh
    Nov 19 '18 at 8:19










  • Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:32










  • The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
    – Mauro ALLEGRANZA
    Nov 19 '18 at 10:33












  • Rewritten in an unambiguous way
    – J.Moh
    Nov 19 '18 at 10:47
















None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
– Lord Shark the Unknown
Nov 19 '18 at 7:15




None, in that I cannot understand either: why have you introduced a $k$, only to use it in the expression $2k/k$ which merely simplifies to $2$?
– Lord Shark the Unknown
Nov 19 '18 at 7:15












/ means such that in my case
– J.Moh
Nov 19 '18 at 8:19




/ means such that in my case
– J.Moh
Nov 19 '18 at 8:19












Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
– Mauro ALLEGRANZA
Nov 19 '18 at 10:32




Impossible to understand ... The first one is an equation : $dfrac {n}{n+1}=2k$.
– Mauro ALLEGRANZA
Nov 19 '18 at 10:32












The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
– Mauro ALLEGRANZA
Nov 19 '18 at 10:33






The second one is a formula : $(dfrac {n}{n+1}=2k) to forall n (dfrac {n}{n+1}=2k)$ whose truth value depends on $n$ and $k$.
– Mauro ALLEGRANZA
Nov 19 '18 at 10:33














Rewritten in an unambiguous way
– J.Moh
Nov 19 '18 at 10:47




Rewritten in an unambiguous way
– J.Moh
Nov 19 '18 at 10:47










1 Answer
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0















Is this true that :




$(n ∈ mathbb Z ⟹ dfrac {n}{(n+1)} = 2k ) ⟹ ∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k text { , for } k ∈ mathbb Z$ ?





The formula :




$dfrac {n}{(n+1)} = 2k$




is about two unspecified numbers $n$ and $k$; it can be either true or false, according to the values we assign to them.



Specifically, the formula is true only for $n=k=0$.



This means that the consequent : $∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k$ is false.



Thus the original formula is false for $n=k=0$ (because in that case we have $text T to text F$, which is $text F$) and true in all other cases (because $text F to text F$ is $text T$).






share|cite|improve this answer























  • / doesn t mean division in my case, it means such that
    – J.Moh
    Nov 19 '18 at 8:18













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1 Answer
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1 Answer
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active

oldest

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active

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0















Is this true that :




$(n ∈ mathbb Z ⟹ dfrac {n}{(n+1)} = 2k ) ⟹ ∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k text { , for } k ∈ mathbb Z$ ?





The formula :




$dfrac {n}{(n+1)} = 2k$




is about two unspecified numbers $n$ and $k$; it can be either true or false, according to the values we assign to them.



Specifically, the formula is true only for $n=k=0$.



This means that the consequent : $∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k$ is false.



Thus the original formula is false for $n=k=0$ (because in that case we have $text T to text F$, which is $text F$) and true in all other cases (because $text F to text F$ is $text T$).






share|cite|improve this answer























  • / doesn t mean division in my case, it means such that
    – J.Moh
    Nov 19 '18 at 8:18


















0















Is this true that :




$(n ∈ mathbb Z ⟹ dfrac {n}{(n+1)} = 2k ) ⟹ ∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k text { , for } k ∈ mathbb Z$ ?





The formula :




$dfrac {n}{(n+1)} = 2k$




is about two unspecified numbers $n$ and $k$; it can be either true or false, according to the values we assign to them.



Specifically, the formula is true only for $n=k=0$.



This means that the consequent : $∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k$ is false.



Thus the original formula is false for $n=k=0$ (because in that case we have $text T to text F$, which is $text F$) and true in all other cases (because $text F to text F$ is $text T$).






share|cite|improve this answer























  • / doesn t mean division in my case, it means such that
    – J.Moh
    Nov 19 '18 at 8:18
















0












0








0







Is this true that :




$(n ∈ mathbb Z ⟹ dfrac {n}{(n+1)} = 2k ) ⟹ ∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k text { , for } k ∈ mathbb Z$ ?





The formula :




$dfrac {n}{(n+1)} = 2k$




is about two unspecified numbers $n$ and $k$; it can be either true or false, according to the values we assign to them.



Specifically, the formula is true only for $n=k=0$.



This means that the consequent : $∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k$ is false.



Thus the original formula is false for $n=k=0$ (because in that case we have $text T to text F$, which is $text F$) and true in all other cases (because $text F to text F$ is $text T$).






share|cite|improve this answer















Is this true that :




$(n ∈ mathbb Z ⟹ dfrac {n}{(n+1)} = 2k ) ⟹ ∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k text { , for } k ∈ mathbb Z$ ?





The formula :




$dfrac {n}{(n+1)} = 2k$




is about two unspecified numbers $n$ and $k$; it can be either true or false, according to the values we assign to them.



Specifically, the formula is true only for $n=k=0$.



This means that the consequent : $∀n ∈ mathbb Z dfrac {n}{(n+1)} = 2k$ is false.



Thus the original formula is false for $n=k=0$ (because in that case we have $text T to text F$, which is $text F$) and true in all other cases (because $text F to text F$ is $text T$).







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Nov 19 '18 at 10:55

























answered Nov 19 '18 at 7:13









Mauro ALLEGRANZA

64.3k448112




64.3k448112












  • / doesn t mean division in my case, it means such that
    – J.Moh
    Nov 19 '18 at 8:18




















  • / doesn t mean division in my case, it means such that
    – J.Moh
    Nov 19 '18 at 8:18


















/ doesn t mean division in my case, it means such that
– J.Moh
Nov 19 '18 at 8:18






/ doesn t mean division in my case, it means such that
– J.Moh
Nov 19 '18 at 8:18




















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