How to define norm on semi vector spaces?

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And and can we give proofs different from vector space norm proofs with its restriction?Can we give standard proofs with the lack of additive identity and additive inverse property?







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    And and can we give proofs different from vector space norm proofs with its restriction?Can we give standard proofs with the lack of additive identity and additive inverse property?







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      up vote
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      And and can we give proofs different from vector space norm proofs with its restriction?Can we give standard proofs with the lack of additive identity and additive inverse property?







      share|cite|improve this question











      And and can we give proofs different from vector space norm proofs with its restriction?Can we give standard proofs with the lack of additive identity and additive inverse property?









      share|cite|improve this question










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      asked Jul 28 at 15:31









      Sherlin

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          No in general. For instance, the gliding hump proof of the uniform boundedness principle fails horribly. Also, the Hahn-Banach theorem can't be proven in the usual way because we can't pass to zero or to a subspace.



          The strategy to obtain results would be to embed the semi vector space into some vector space. This works e.g. when the semi vector space has some sort of "basis".






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          • Thnx can u give me some more properties..
            – Sherlin
            Jul 28 at 15:40










          • It would help greatly if you had a particular semi vector space in mind...
            – AlgebraicsAnonymous
            Jul 28 at 15:41










          • If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
            – AlgebraicsAnonymous
            Jul 28 at 15:43










          • Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
            – Sherlin
            Jul 28 at 15:50










          • Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
            – AlgebraicsAnonymous
            Jul 28 at 15:52










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          1 Answer
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          1 Answer
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          active

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          up vote
          0
          down vote













          No in general. For instance, the gliding hump proof of the uniform boundedness principle fails horribly. Also, the Hahn-Banach theorem can't be proven in the usual way because we can't pass to zero or to a subspace.



          The strategy to obtain results would be to embed the semi vector space into some vector space. This works e.g. when the semi vector space has some sort of "basis".






          share|cite|improve this answer





















          • Thnx can u give me some more properties..
            – Sherlin
            Jul 28 at 15:40










          • It would help greatly if you had a particular semi vector space in mind...
            – AlgebraicsAnonymous
            Jul 28 at 15:41










          • If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
            – AlgebraicsAnonymous
            Jul 28 at 15:43










          • Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
            – Sherlin
            Jul 28 at 15:50










          • Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
            – AlgebraicsAnonymous
            Jul 28 at 15:52














          up vote
          0
          down vote













          No in general. For instance, the gliding hump proof of the uniform boundedness principle fails horribly. Also, the Hahn-Banach theorem can't be proven in the usual way because we can't pass to zero or to a subspace.



          The strategy to obtain results would be to embed the semi vector space into some vector space. This works e.g. when the semi vector space has some sort of "basis".






          share|cite|improve this answer





















          • Thnx can u give me some more properties..
            – Sherlin
            Jul 28 at 15:40










          • It would help greatly if you had a particular semi vector space in mind...
            – AlgebraicsAnonymous
            Jul 28 at 15:41










          • If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
            – AlgebraicsAnonymous
            Jul 28 at 15:43










          • Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
            – Sherlin
            Jul 28 at 15:50










          • Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
            – AlgebraicsAnonymous
            Jul 28 at 15:52












          up vote
          0
          down vote










          up vote
          0
          down vote









          No in general. For instance, the gliding hump proof of the uniform boundedness principle fails horribly. Also, the Hahn-Banach theorem can't be proven in the usual way because we can't pass to zero or to a subspace.



          The strategy to obtain results would be to embed the semi vector space into some vector space. This works e.g. when the semi vector space has some sort of "basis".






          share|cite|improve this answer













          No in general. For instance, the gliding hump proof of the uniform boundedness principle fails horribly. Also, the Hahn-Banach theorem can't be proven in the usual way because we can't pass to zero or to a subspace.



          The strategy to obtain results would be to embed the semi vector space into some vector space. This works e.g. when the semi vector space has some sort of "basis".







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Jul 28 at 15:36









          AlgebraicsAnonymous

          66611




          66611











          • Thnx can u give me some more properties..
            – Sherlin
            Jul 28 at 15:40










          • It would help greatly if you had a particular semi vector space in mind...
            – AlgebraicsAnonymous
            Jul 28 at 15:41










          • If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
            – AlgebraicsAnonymous
            Jul 28 at 15:43










          • Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
            – Sherlin
            Jul 28 at 15:50










          • Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
            – AlgebraicsAnonymous
            Jul 28 at 15:52
















          • Thnx can u give me some more properties..
            – Sherlin
            Jul 28 at 15:40










          • It would help greatly if you had a particular semi vector space in mind...
            – AlgebraicsAnonymous
            Jul 28 at 15:41










          • If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
            – AlgebraicsAnonymous
            Jul 28 at 15:43










          • Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
            – Sherlin
            Jul 28 at 15:50










          • Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
            – AlgebraicsAnonymous
            Jul 28 at 15:52















          Thnx can u give me some more properties..
          – Sherlin
          Jul 28 at 15:40




          Thnx can u give me some more properties..
          – Sherlin
          Jul 28 at 15:40












          It would help greatly if you had a particular semi vector space in mind...
          – AlgebraicsAnonymous
          Jul 28 at 15:41




          It would help greatly if you had a particular semi vector space in mind...
          – AlgebraicsAnonymous
          Jul 28 at 15:41












          If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
          – AlgebraicsAnonymous
          Jul 28 at 15:43




          If you, for instance, were to talk about a convex cone in a Hilbert space, then things would work fine...
          – AlgebraicsAnonymous
          Jul 28 at 15:43












          Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
          – Sherlin
          Jul 28 at 15:50




          Can it work with 0 included and defining inner product on it and can we get different proofs ..i am specific abt the semi field of positive real numbers can u give me some simple semi vector spaces so that i can try to bring its norm properties
          – Sherlin
          Jul 28 at 15:50












          Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
          – AlgebraicsAnonymous
          Jul 28 at 15:52




          Possibly one could formally define the extension to the real numbers as a positive and negative part, just like the Grothendieck group construction. In this case, one would have an embedding and could get the results one wants from that.
          – AlgebraicsAnonymous
          Jul 28 at 15:52












           

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