Characteristic of a field is not equal to zero











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Let $F$ be a field such that for every $x in F$ there exists a $k >0$ such that $x^k=1$. Does this imply that the characteristic of $F$ is strictly greater than zero?










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    Let $F$ be a field such that for every $x in F$ there exists a $k >0$ such that $x^k=1$. Does this imply that the characteristic of $F$ is strictly greater than zero?










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      up vote
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      Let $F$ be a field such that for every $x in F$ there exists a $k >0$ such that $x^k=1$. Does this imply that the characteristic of $F$ is strictly greater than zero?










      share|cite|improve this question













      Let $F$ be a field such that for every $x in F$ there exists a $k >0$ such that $x^k=1$. Does this imply that the characteristic of $F$ is strictly greater than zero?







      field-theory






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      asked 16 hours ago









      J.Bosser

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          Yes. If the characteristic is zero then the prime subfield is isomorphic to $mathbb{Q}$, and this contains elements - e.g. 2 - whose nonzero powers are never equal to 1.






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            Every field $F$ of characteristic $0$ contains (up to isomorphism) the field of rational numbers. If you take the rational number $frac{1}{2}$, say, then there is no integer $k>0$ such that $left(frac{1}{2}right)^k = 1$.



            For a finite field with $q$ (prime power) elements, one has $x^{q-1}=1$ for each element $xne 0$ and $x^q=x$ for each element $x$.






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              2 Answers
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              active

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              2 Answers
              2






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              active

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              active

              oldest

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              up vote
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              down vote



              accepted










              Yes. If the characteristic is zero then the prime subfield is isomorphic to $mathbb{Q}$, and this contains elements - e.g. 2 - whose nonzero powers are never equal to 1.






              share|cite|improve this answer

























                up vote
                4
                down vote



                accepted










                Yes. If the characteristic is zero then the prime subfield is isomorphic to $mathbb{Q}$, and this contains elements - e.g. 2 - whose nonzero powers are never equal to 1.






                share|cite|improve this answer























                  up vote
                  4
                  down vote



                  accepted







                  up vote
                  4
                  down vote



                  accepted






                  Yes. If the characteristic is zero then the prime subfield is isomorphic to $mathbb{Q}$, and this contains elements - e.g. 2 - whose nonzero powers are never equal to 1.






                  share|cite|improve this answer












                  Yes. If the characteristic is zero then the prime subfield is isomorphic to $mathbb{Q}$, and this contains elements - e.g. 2 - whose nonzero powers are never equal to 1.







                  share|cite|improve this answer












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                  answered 16 hours ago









                  Matthew Towers

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                      Every field $F$ of characteristic $0$ contains (up to isomorphism) the field of rational numbers. If you take the rational number $frac{1}{2}$, say, then there is no integer $k>0$ such that $left(frac{1}{2}right)^k = 1$.



                      For a finite field with $q$ (prime power) elements, one has $x^{q-1}=1$ for each element $xne 0$ and $x^q=x$ for each element $x$.






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                        up vote
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                        Every field $F$ of characteristic $0$ contains (up to isomorphism) the field of rational numbers. If you take the rational number $frac{1}{2}$, say, then there is no integer $k>0$ such that $left(frac{1}{2}right)^k = 1$.



                        For a finite field with $q$ (prime power) elements, one has $x^{q-1}=1$ for each element $xne 0$ and $x^q=x$ for each element $x$.






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                          up vote
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                          Every field $F$ of characteristic $0$ contains (up to isomorphism) the field of rational numbers. If you take the rational number $frac{1}{2}$, say, then there is no integer $k>0$ such that $left(frac{1}{2}right)^k = 1$.



                          For a finite field with $q$ (prime power) elements, one has $x^{q-1}=1$ for each element $xne 0$ and $x^q=x$ for each element $x$.






                          share|cite|improve this answer














                          Every field $F$ of characteristic $0$ contains (up to isomorphism) the field of rational numbers. If you take the rational number $frac{1}{2}$, say, then there is no integer $k>0$ such that $left(frac{1}{2}right)^k = 1$.



                          For a finite field with $q$ (prime power) elements, one has $x^{q-1}=1$ for each element $xne 0$ and $x^q=x$ for each element $x$.







                          share|cite|improve this answer














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                          share|cite|improve this answer








                          edited 16 hours ago

























                          answered 16 hours ago









                          Wuestenfux

                          3,0351410




                          3,0351410






























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