Proving 2 languages are equal.











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I am quite new to Discrete Math and having lots of troubles solving the problems in it.



Currently, I am struggling with a problem:



Prove by induction that if $A$ and $B$ are regular expressions over one-letter alphabet and if $n$ is any natural, prove that languages $(AB)^n$ and $A^nB^n$ are equal.



Thanks










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  • Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
    – Fabio Somenzi
    Nov 19 at 5:32










  • Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
    – Alan Bui
    Nov 19 at 5:53










  • If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
    – Fabio Somenzi
    Nov 19 at 5:56










  • @FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
    – keoxkeox
    Nov 19 at 6:00












  • @keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
    – Fabio Somenzi
    Nov 19 at 6:01















up vote
0
down vote

favorite












I am quite new to Discrete Math and having lots of troubles solving the problems in it.



Currently, I am struggling with a problem:



Prove by induction that if $A$ and $B$ are regular expressions over one-letter alphabet and if $n$ is any natural, prove that languages $(AB)^n$ and $A^nB^n$ are equal.



Thanks










share|cite|improve this question
























  • Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
    – Fabio Somenzi
    Nov 19 at 5:32










  • Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
    – Alan Bui
    Nov 19 at 5:53










  • If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
    – Fabio Somenzi
    Nov 19 at 5:56










  • @FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
    – keoxkeox
    Nov 19 at 6:00












  • @keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
    – Fabio Somenzi
    Nov 19 at 6:01













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I am quite new to Discrete Math and having lots of troubles solving the problems in it.



Currently, I am struggling with a problem:



Prove by induction that if $A$ and $B$ are regular expressions over one-letter alphabet and if $n$ is any natural, prove that languages $(AB)^n$ and $A^nB^n$ are equal.



Thanks










share|cite|improve this question















I am quite new to Discrete Math and having lots of troubles solving the problems in it.



Currently, I am struggling with a problem:



Prove by induction that if $A$ and $B$ are regular expressions over one-letter alphabet and if $n$ is any natural, prove that languages $(AB)^n$ and $A^nB^n$ are equal.



Thanks







discrete-mathematics regular-expressions






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 19 at 5:55

























asked Nov 19 at 5:06









Alan Bui

113




113












  • Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
    – Fabio Somenzi
    Nov 19 at 5:32










  • Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
    – Alan Bui
    Nov 19 at 5:53










  • If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
    – Fabio Somenzi
    Nov 19 at 5:56










  • @FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
    – keoxkeox
    Nov 19 at 6:00












  • @keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
    – Fabio Somenzi
    Nov 19 at 6:01


















  • Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
    – Fabio Somenzi
    Nov 19 at 5:32










  • Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
    – Alan Bui
    Nov 19 at 5:53










  • If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
    – Fabio Somenzi
    Nov 19 at 5:56










  • @FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
    – keoxkeox
    Nov 19 at 6:00












  • @keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
    – Fabio Somenzi
    Nov 19 at 6:01
















Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
– Fabio Somenzi
Nov 19 at 5:32




Have you tried some simple example? If the alphabet is ${1}$, $A=11$ and $B=1$, what do you get?
– Fabio Somenzi
Nov 19 at 5:32












Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
– Alan Bui
Nov 19 at 5:53




Sorry to say this but I am pretty much lost and do not know where to start my thing. I need some examples so I can follow it.
– Alan Bui
Nov 19 at 5:53












If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
– Fabio Somenzi
Nov 19 at 5:56




If $A$ and $B$ are as above and $n=2$, $(AB)^n = (111)^2 = 111111$ and $A^nB^n = (11)^2(1)^2 = 111111$.
– Fabio Somenzi
Nov 19 at 5:56












@FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
– keoxkeox
Nov 19 at 6:00






@FabioSomenzi can you please do an example with $A=a$ and $B=b$ where $a neq b$ or $a$ and $b$ are not concats of each other?
– keoxkeox
Nov 19 at 6:00














@keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
– Fabio Somenzi
Nov 19 at 6:01




@keoxkeox The alphabet is supposed to have only one letter; otherwise the claim is obviously wrong.
– Fabio Somenzi
Nov 19 at 6:01















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