Proof verification- $ sigma $ - Algebra, Algebra, Ring












2












$begingroup$


I want to prove following for a set $ X neq emptyset $ :
$ M subset P(X) $, where $ P(X) $ is the power set.



1) Any Ring is an Algebra



2) Any Algebra is a Ring



3) Any Ring is a $ sigma $ -Algebra



4) Any Algebra is a $ sigma $- Algebra



5) Any $ sigma $- Algebra is an Algebra



For a set $ X neq emptyset $, $M$ is



a) A Ring if




  • $ emptyset in M$


  • $ A,B in M rightarrow A cup B in M $


  • $ A,B in M rightarrow B backslash A in M $



b) An Algebra, if $ M$ Ring , and $ X in M $



c) A $ sigma $-Algebra if




  • $ X in M $


  • $ A in M rightarrow X backslash A in M $


  • $ (A_i)_{i in mathbb{N}} in M rightarrow cup_{i=0}^{ infty} A_i in M $





for 1)
For $ A subset X $ is M:={ emptyset , A} a Ring, but for $ A neq X$ not an Algebra.



2)
let be $ A,B in M $



$ A backslash B = ( A^c cup B )^c in M $
So M is also a ring.



3)
I guess I can use the same example as for 1)?



4) let be $ X= mathbb{N} , M:= { A subset X : A $ or $ A^c $ finite $}$
is this a right example for an Alegbra , which is not a s.Algeba?



5)
$A,B in M $



$ X= X backslash emptyset in M $



$ Abackslash B = A cap B^c = ( A^c cup B)^c in M $



any union you can discribe as :
$ A cup B = A cup B cup emptyset cup ...emptyset in M $



so any s. Algebra is also an Algebra.



are my arguments correct and formally right? any adjustments?
Appreciate any of your help !










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is the role of the set $;X;$ in all those question ...??
    $endgroup$
    – DonAntonio
    Jan 23 at 13:58










  • $begingroup$
    it's a random set..if that's what you mean.?
    $endgroup$
    – wondering1123
    Jan 23 at 16:47










  • $begingroup$
    Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
    $endgroup$
    – reuns
    Jan 23 at 22:03


















2












$begingroup$


I want to prove following for a set $ X neq emptyset $ :
$ M subset P(X) $, where $ P(X) $ is the power set.



1) Any Ring is an Algebra



2) Any Algebra is a Ring



3) Any Ring is a $ sigma $ -Algebra



4) Any Algebra is a $ sigma $- Algebra



5) Any $ sigma $- Algebra is an Algebra



For a set $ X neq emptyset $, $M$ is



a) A Ring if




  • $ emptyset in M$


  • $ A,B in M rightarrow A cup B in M $


  • $ A,B in M rightarrow B backslash A in M $



b) An Algebra, if $ M$ Ring , and $ X in M $



c) A $ sigma $-Algebra if




  • $ X in M $


  • $ A in M rightarrow X backslash A in M $


  • $ (A_i)_{i in mathbb{N}} in M rightarrow cup_{i=0}^{ infty} A_i in M $





for 1)
For $ A subset X $ is M:={ emptyset , A} a Ring, but for $ A neq X$ not an Algebra.



2)
let be $ A,B in M $



$ A backslash B = ( A^c cup B )^c in M $
So M is also a ring.



3)
I guess I can use the same example as for 1)?



4) let be $ X= mathbb{N} , M:= { A subset X : A $ or $ A^c $ finite $}$
is this a right example for an Alegbra , which is not a s.Algeba?



5)
$A,B in M $



$ X= X backslash emptyset in M $



$ Abackslash B = A cap B^c = ( A^c cup B)^c in M $



any union you can discribe as :
$ A cup B = A cup B cup emptyset cup ...emptyset in M $



so any s. Algebra is also an Algebra.



are my arguments correct and formally right? any adjustments?
Appreciate any of your help !










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is the role of the set $;X;$ in all those question ...??
    $endgroup$
    – DonAntonio
    Jan 23 at 13:58










  • $begingroup$
    it's a random set..if that's what you mean.?
    $endgroup$
    – wondering1123
    Jan 23 at 16:47










  • $begingroup$
    Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
    $endgroup$
    – reuns
    Jan 23 at 22:03
















2












2








2





$begingroup$


I want to prove following for a set $ X neq emptyset $ :
$ M subset P(X) $, where $ P(X) $ is the power set.



1) Any Ring is an Algebra



2) Any Algebra is a Ring



3) Any Ring is a $ sigma $ -Algebra



4) Any Algebra is a $ sigma $- Algebra



5) Any $ sigma $- Algebra is an Algebra



For a set $ X neq emptyset $, $M$ is



a) A Ring if




  • $ emptyset in M$


  • $ A,B in M rightarrow A cup B in M $


  • $ A,B in M rightarrow B backslash A in M $



b) An Algebra, if $ M$ Ring , and $ X in M $



c) A $ sigma $-Algebra if




  • $ X in M $


  • $ A in M rightarrow X backslash A in M $


  • $ (A_i)_{i in mathbb{N}} in M rightarrow cup_{i=0}^{ infty} A_i in M $





for 1)
For $ A subset X $ is M:={ emptyset , A} a Ring, but for $ A neq X$ not an Algebra.



2)
let be $ A,B in M $



$ A backslash B = ( A^c cup B )^c in M $
So M is also a ring.



3)
I guess I can use the same example as for 1)?



4) let be $ X= mathbb{N} , M:= { A subset X : A $ or $ A^c $ finite $}$
is this a right example for an Alegbra , which is not a s.Algeba?



5)
$A,B in M $



$ X= X backslash emptyset in M $



$ Abackslash B = A cap B^c = ( A^c cup B)^c in M $



any union you can discribe as :
$ A cup B = A cup B cup emptyset cup ...emptyset in M $



so any s. Algebra is also an Algebra.



are my arguments correct and formally right? any adjustments?
Appreciate any of your help !










share|cite|improve this question











$endgroup$




I want to prove following for a set $ X neq emptyset $ :
$ M subset P(X) $, where $ P(X) $ is the power set.



1) Any Ring is an Algebra



2) Any Algebra is a Ring



3) Any Ring is a $ sigma $ -Algebra



4) Any Algebra is a $ sigma $- Algebra



5) Any $ sigma $- Algebra is an Algebra



For a set $ X neq emptyset $, $M$ is



a) A Ring if




  • $ emptyset in M$


  • $ A,B in M rightarrow A cup B in M $


  • $ A,B in M rightarrow B backslash A in M $



b) An Algebra, if $ M$ Ring , and $ X in M $



c) A $ sigma $-Algebra if




  • $ X in M $


  • $ A in M rightarrow X backslash A in M $


  • $ (A_i)_{i in mathbb{N}} in M rightarrow cup_{i=0}^{ infty} A_i in M $





for 1)
For $ A subset X $ is M:={ emptyset , A} a Ring, but for $ A neq X$ not an Algebra.



2)
let be $ A,B in M $



$ A backslash B = ( A^c cup B )^c in M $
So M is also a ring.



3)
I guess I can use the same example as for 1)?



4) let be $ X= mathbb{N} , M:= { A subset X : A $ or $ A^c $ finite $}$
is this a right example for an Alegbra , which is not a s.Algeba?



5)
$A,B in M $



$ X= X backslash emptyset in M $



$ Abackslash B = A cap B^c = ( A^c cup B)^c in M $



any union you can discribe as :
$ A cup B = A cup B cup emptyset cup ...emptyset in M $



so any s. Algebra is also an Algebra.



are my arguments correct and formally right? any adjustments?
Appreciate any of your help !







real-analysis measure-theory proof-verification elementary-set-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 23 at 22:49









Andrés E. Caicedo

65.7k8160250




65.7k8160250










asked Jan 23 at 13:51









wondering1123wondering1123

14911




14911












  • $begingroup$
    What is the role of the set $;X;$ in all those question ...??
    $endgroup$
    – DonAntonio
    Jan 23 at 13:58










  • $begingroup$
    it's a random set..if that's what you mean.?
    $endgroup$
    – wondering1123
    Jan 23 at 16:47










  • $begingroup$
    Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
    $endgroup$
    – reuns
    Jan 23 at 22:03




















  • $begingroup$
    What is the role of the set $;X;$ in all those question ...??
    $endgroup$
    – DonAntonio
    Jan 23 at 13:58










  • $begingroup$
    it's a random set..if that's what you mean.?
    $endgroup$
    – wondering1123
    Jan 23 at 16:47










  • $begingroup$
    Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
    $endgroup$
    – reuns
    Jan 23 at 22:03


















$begingroup$
What is the role of the set $;X;$ in all those question ...??
$endgroup$
– DonAntonio
Jan 23 at 13:58




$begingroup$
What is the role of the set $;X;$ in all those question ...??
$endgroup$
– DonAntonio
Jan 23 at 13:58












$begingroup$
it's a random set..if that's what you mean.?
$endgroup$
– wondering1123
Jan 23 at 16:47




$begingroup$
it's a random set..if that's what you mean.?
$endgroup$
– wondering1123
Jan 23 at 16:47












$begingroup$
Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
$endgroup$
– reuns
Jan 23 at 22:03






$begingroup$
Do you see how to go from boolean algebra on $M $ to $sigma$-algebra on $M$ ? $A . B = A cap B$ and $A + B =...$
$endgroup$
– reuns
Jan 23 at 22:03












0






active

oldest

votes











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
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3084491%2fproof-verification-sigma-algebra-algebra-ring%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































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.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3084491%2fproof-verification-sigma-algebra-algebra-ring%23new-answer', 'question_page');
}
);

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







Popular posts from this blog

Can a sorcerer learn a 5th-level spell early by creating spell slots using the Font of Magic feature?

Does disintegrating a polymorphed enemy still kill it after the 2018 errata?

A Topological Invariant for $pi_3(U(n))$