Finite field generator exponentiation properties
$begingroup$
For a finite integer field $mathbb{Z}_n$ with a generator $g$ and $xinmathbb{Z}_n$, a property I do not understand arises and I have not come across an explanation for it. If another set of values $x_1=n+x, x_2=2n+xdots$ then $g^{x}neq g^{x_1}neq g^{x_2}dots$. Why is this? I've noticed and conjectured that for an $x_k=kn+x$, $g^{x}=g^{x_k +k}$ at least for several examples I have been toying with to get a feel for the mechanics. Since all these values are members of the same congruence class, I'd expect them to generate identical field elements. Is it because the multiplicative subgroup is of order $n-1 $ due to the removal of the additive identity? I'd appreciate any guidance and clarification on this matter.
abstract-algebra finite-fields
$endgroup$
|
show 1 more comment
$begingroup$
For a finite integer field $mathbb{Z}_n$ with a generator $g$ and $xinmathbb{Z}_n$, a property I do not understand arises and I have not come across an explanation for it. If another set of values $x_1=n+x, x_2=2n+xdots$ then $g^{x}neq g^{x_1}neq g^{x_2}dots$. Why is this? I've noticed and conjectured that for an $x_k=kn+x$, $g^{x}=g^{x_k +k}$ at least for several examples I have been toying with to get a feel for the mechanics. Since all these values are members of the same congruence class, I'd expect them to generate identical field elements. Is it because the multiplicative subgroup is of order $n-1 $ due to the removal of the additive identity? I'd appreciate any guidance and clarification on this matter.
abstract-algebra finite-fields
$endgroup$
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
1
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
1
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
1
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47
|
show 1 more comment
$begingroup$
For a finite integer field $mathbb{Z}_n$ with a generator $g$ and $xinmathbb{Z}_n$, a property I do not understand arises and I have not come across an explanation for it. If another set of values $x_1=n+x, x_2=2n+xdots$ then $g^{x}neq g^{x_1}neq g^{x_2}dots$. Why is this? I've noticed and conjectured that for an $x_k=kn+x$, $g^{x}=g^{x_k +k}$ at least for several examples I have been toying with to get a feel for the mechanics. Since all these values are members of the same congruence class, I'd expect them to generate identical field elements. Is it because the multiplicative subgroup is of order $n-1 $ due to the removal of the additive identity? I'd appreciate any guidance and clarification on this matter.
abstract-algebra finite-fields
$endgroup$
For a finite integer field $mathbb{Z}_n$ with a generator $g$ and $xinmathbb{Z}_n$, a property I do not understand arises and I have not come across an explanation for it. If another set of values $x_1=n+x, x_2=2n+xdots$ then $g^{x}neq g^{x_1}neq g^{x_2}dots$. Why is this? I've noticed and conjectured that for an $x_k=kn+x$, $g^{x}=g^{x_k +k}$ at least for several examples I have been toying with to get a feel for the mechanics. Since all these values are members of the same congruence class, I'd expect them to generate identical field elements. Is it because the multiplicative subgroup is of order $n-1 $ due to the removal of the additive identity? I'd appreciate any guidance and clarification on this matter.
abstract-algebra finite-fields
abstract-algebra finite-fields
asked Dec 3 '18 at 23:08
Ken GossKen Goss
1035
1035
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
1
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
1
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
1
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47
|
show 1 more comment
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
1
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
1
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
1
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
1
1
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
1
1
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
1
1
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47
|
show 1 more comment
1 Answer
1
active
oldest
votes
$begingroup$
If your $n$ is a prime number, by lil' Fermat, we have $g^nequiv gmod n$, hence
$$g^{x_k}=g^{x+k}enspaceforall kinmathbf Z.$$
$endgroup$
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024848%2ffinite-field-generator-exponentiation-properties%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
If your $n$ is a prime number, by lil' Fermat, we have $g^nequiv gmod n$, hence
$$g^{x_k}=g^{x+k}enspaceforall kinmathbf Z.$$
$endgroup$
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
add a comment |
$begingroup$
If your $n$ is a prime number, by lil' Fermat, we have $g^nequiv gmod n$, hence
$$g^{x_k}=g^{x+k}enspaceforall kinmathbf Z.$$
$endgroup$
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
add a comment |
$begingroup$
If your $n$ is a prime number, by lil' Fermat, we have $g^nequiv gmod n$, hence
$$g^{x_k}=g^{x+k}enspaceforall kinmathbf Z.$$
$endgroup$
If your $n$ is a prime number, by lil' Fermat, we have $g^nequiv gmod n$, hence
$$g^{x_k}=g^{x+k}enspaceforall kinmathbf Z.$$
edited Dec 3 '18 at 23:41
answered Dec 3 '18 at 23:33
BernardBernard
119k740113
119k740113
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
add a comment |
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
$begingroup$
Ah, so straight-forward. I just didn't make the connection. Thank you! Between your answer and Qiaochu Yuan's comments it is clear to me now.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:53
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024848%2ffinite-field-generator-exponentiation-properties%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
$begingroup$
Is $n$ a prime number?
$endgroup$
– Bernard
Dec 3 '18 at 23:19
1
$begingroup$
Every element of $mathbb{F}_p$ satisfies $g^p = g$, so $g^{2p} = g^2, g^{3p} = g^3$, etc. In other words, since the multiplicative group has order $p - 1$, the exponents are numbers that make sense $bmod (p - 1)$, not $bmod p$. In general exponentiation takes in two different types of objects as input; the fact that exponentiation seems like it takes in the same types of objects as input over the real numbers is misleading.
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:22
$begingroup$
@Bernard yes it's a prime modulus, sorry for not including that detail explicitly.
$endgroup$
– Ken Goss
Dec 3 '18 at 23:38
1
$begingroup$
I have a long rant about this; I wrote a (bad) version of it here: math.stackexchange.com/questions/56663/…
$endgroup$
– Qiaochu Yuan
Dec 3 '18 at 23:45
1
$begingroup$
@QiaochuYuan you’re right that is a long rant, but I rather like it.
$endgroup$
– Randall
Dec 4 '18 at 0:47