Continuity of two variables in toplogical space .












1














Let $T$ is subset of real numbers .Let $k$ is any number which is not in $T$ .



Define $$kT ={ kt : t in T}. $$
Let $W$ is toplogy(not usual) on $T$ , then can you prove that :



$$H={ kU : U in W }$$ is topology for $kT$ .



And is the function $f:kTtimes kTto kT$ continuous with respect to $H$ if it is defined as
$$f (kt,ks)=k (t+s ),$$ for $t ,s in T$?



Note that it is given : for every $s,t in T $, $s+t$ belongs to $T .$










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  • The second line is unclear. Can you rephrase it?
    – caffeinemachine
    Dec 27 '18 at 8:16










  • Kavi Rama Murthy can you explain it little more. How by definition it will hold?
    – Guru
    Dec 27 '18 at 9:41










  • @Guru I had misread the second part. I have posted an answer now.
    – Kavi Rama Murthy
    Dec 27 '18 at 10:04
















1














Let $T$ is subset of real numbers .Let $k$ is any number which is not in $T$ .



Define $$kT ={ kt : t in T}. $$
Let $W$ is toplogy(not usual) on $T$ , then can you prove that :



$$H={ kU : U in W }$$ is topology for $kT$ .



And is the function $f:kTtimes kTto kT$ continuous with respect to $H$ if it is defined as
$$f (kt,ks)=k (t+s ),$$ for $t ,s in T$?



Note that it is given : for every $s,t in T $, $s+t$ belongs to $T .$










share|cite|improve this question









New contributor




Guru is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • The second line is unclear. Can you rephrase it?
    – caffeinemachine
    Dec 27 '18 at 8:16










  • Kavi Rama Murthy can you explain it little more. How by definition it will hold?
    – Guru
    Dec 27 '18 at 9:41










  • @Guru I had misread the second part. I have posted an answer now.
    – Kavi Rama Murthy
    Dec 27 '18 at 10:04














1












1








1







Let $T$ is subset of real numbers .Let $k$ is any number which is not in $T$ .



Define $$kT ={ kt : t in T}. $$
Let $W$ is toplogy(not usual) on $T$ , then can you prove that :



$$H={ kU : U in W }$$ is topology for $kT$ .



And is the function $f:kTtimes kTto kT$ continuous with respect to $H$ if it is defined as
$$f (kt,ks)=k (t+s ),$$ for $t ,s in T$?



Note that it is given : for every $s,t in T $, $s+t$ belongs to $T .$










share|cite|improve this question









New contributor




Guru is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











Let $T$ is subset of real numbers .Let $k$ is any number which is not in $T$ .



Define $$kT ={ kt : t in T}. $$
Let $W$ is toplogy(not usual) on $T$ , then can you prove that :



$$H={ kU : U in W }$$ is topology for $kT$ .



And is the function $f:kTtimes kTto kT$ continuous with respect to $H$ if it is defined as
$$f (kt,ks)=k (t+s ),$$ for $t ,s in T$?



Note that it is given : for every $s,t in T $, $s+t$ belongs to $T .$







real-analysis general-topology continuity metric-spaces metrizability






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Check out our Code of Conduct.











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edited Dec 27 '18 at 8:50









MotylaNogaTomkaMazura

6,542917




6,542917






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asked Dec 27 '18 at 8:12









Guru

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63




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New contributor





Guru is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Guru is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • The second line is unclear. Can you rephrase it?
    – caffeinemachine
    Dec 27 '18 at 8:16










  • Kavi Rama Murthy can you explain it little more. How by definition it will hold?
    – Guru
    Dec 27 '18 at 9:41










  • @Guru I had misread the second part. I have posted an answer now.
    – Kavi Rama Murthy
    Dec 27 '18 at 10:04


















  • The second line is unclear. Can you rephrase it?
    – caffeinemachine
    Dec 27 '18 at 8:16










  • Kavi Rama Murthy can you explain it little more. How by definition it will hold?
    – Guru
    Dec 27 '18 at 9:41










  • @Guru I had misread the second part. I have posted an answer now.
    – Kavi Rama Murthy
    Dec 27 '18 at 10:04
















The second line is unclear. Can you rephrase it?
– caffeinemachine
Dec 27 '18 at 8:16




The second line is unclear. Can you rephrase it?
– caffeinemachine
Dec 27 '18 at 8:16












Kavi Rama Murthy can you explain it little more. How by definition it will hold?
– Guru
Dec 27 '18 at 9:41




Kavi Rama Murthy can you explain it little more. How by definition it will hold?
– Guru
Dec 27 '18 at 9:41












@Guru I had misread the second part. I have posted an answer now.
– Kavi Rama Murthy
Dec 27 '18 at 10:04




@Guru I had misread the second part. I have posted an answer now.
– Kavi Rama Murthy
Dec 27 '18 at 10:04










1 Answer
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Thew first part follows from the relations $k(cup U_i)=cup kU_i$, $k(U cap V)=kUcap kV$, $kemptyset =kemptyset$. For the second part, taking $T=(1,infty)$ and $k=1$ you are asking if $(t,s) to t+s$ is continuous for ANY topology on $(1,infty)$. This is not true.






share|cite|improve this answer





















  • Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
    – Guru
    Dec 27 '18 at 11:06












  • @Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
    – Kavi Rama Murthy
    Dec 27 '18 at 11:45












  • Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
    – Guru
    Dec 27 '18 at 14:58











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1 Answer
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Thew first part follows from the relations $k(cup U_i)=cup kU_i$, $k(U cap V)=kUcap kV$, $kemptyset =kemptyset$. For the second part, taking $T=(1,infty)$ and $k=1$ you are asking if $(t,s) to t+s$ is continuous for ANY topology on $(1,infty)$. This is not true.






share|cite|improve this answer





















  • Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
    – Guru
    Dec 27 '18 at 11:06












  • @Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
    – Kavi Rama Murthy
    Dec 27 '18 at 11:45












  • Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
    – Guru
    Dec 27 '18 at 14:58
















0














Thew first part follows from the relations $k(cup U_i)=cup kU_i$, $k(U cap V)=kUcap kV$, $kemptyset =kemptyset$. For the second part, taking $T=(1,infty)$ and $k=1$ you are asking if $(t,s) to t+s$ is continuous for ANY topology on $(1,infty)$. This is not true.






share|cite|improve this answer





















  • Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
    – Guru
    Dec 27 '18 at 11:06












  • @Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
    – Kavi Rama Murthy
    Dec 27 '18 at 11:45












  • Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
    – Guru
    Dec 27 '18 at 14:58














0












0








0






Thew first part follows from the relations $k(cup U_i)=cup kU_i$, $k(U cap V)=kUcap kV$, $kemptyset =kemptyset$. For the second part, taking $T=(1,infty)$ and $k=1$ you are asking if $(t,s) to t+s$ is continuous for ANY topology on $(1,infty)$. This is not true.






share|cite|improve this answer












Thew first part follows from the relations $k(cup U_i)=cup kU_i$, $k(U cap V)=kUcap kV$, $kemptyset =kemptyset$. For the second part, taking $T=(1,infty)$ and $k=1$ you are asking if $(t,s) to t+s$ is continuous for ANY topology on $(1,infty)$. This is not true.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 27 '18 at 9:56









Kavi Rama Murthy

50.5k31854




50.5k31854












  • Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
    – Guru
    Dec 27 '18 at 11:06












  • @Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
    – Kavi Rama Murthy
    Dec 27 '18 at 11:45












  • Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
    – Guru
    Dec 27 '18 at 14:58


















  • Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
    – Guru
    Dec 27 '18 at 11:06












  • @Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
    – Kavi Rama Murthy
    Dec 27 '18 at 11:45












  • Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
    – Guru
    Dec 27 '18 at 14:58
















Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
– Guru
Dec 27 '18 at 11:06






Kavi Rama murthy thanks for your reply .But i am asking how can we check continuity of above function with respect to topology H? Not on arbitrary toplogy .Thanks onece again.
– Guru
Dec 27 '18 at 11:06














@Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
– Kavi Rama Murthy
Dec 27 '18 at 11:45






@Guru When $k=1$ $kT=T$ and the topology on $kT$ is same as the topology on $T$. The topology yon $T$ is not specified. It can be any topology. So the map $(t,s) to t+s$ need not be continuous.
– Kavi Rama Murthy
Dec 27 '18 at 11:45














Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
– Guru
Dec 27 '18 at 14:58




Ok... thanks a lot sir , kavi Rama murthy .one last qeustion " which book is the best to understand the concept of " toplogical fields " , homeomorphism between toplogical fields and homeomorphism on field structure together with isomorphisim for beggner"?
– Guru
Dec 27 '18 at 14:58










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