how to check quasi convexity using hessian matrix ?

[akanksha]

[Akshay Jain]

we use bordered hessian matrix to chek for Quasi concavity/convexity of a function
click here and read theorem 14 and example 4 on pages 10-11

[Homer Simpson]

 thanks

[Dreyfus]

Only quasi concavity can be checked through bordered hessian

[Dreyfus]

Its really strange Akshay...acc to Chiang there is no way to check quasiconvexity through bordered hessian.....

[Anakin Skywalker]

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[SoniaKapoor]

Anirudh pls elaborate your point....how to check??

[Anakin Skywalker]

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[Granpa Simpson]

The conditions are as follows:
Quasiconcavity: If there are odd number of variables then the bordered hessians will alternate in sign starting with a negative, however if there are even number of variables then bordered hessians will be positive.
Quasiconvexity: Bordered hessians will be negative for all n (no of variables).

[SoniaKapoor]

Thanxx Anirudh , Subhayu i understood. Can u quote an eg .It will become much clearer then. Thnkxxx

[Granpa Simpson]

Sonia: follow this link
https://www.economics.utoronto.ca/osborne/MathTutorial/QCC.HTM

[akanksha]

thanks everybody
@subhayu the link u mentioned was quite helpful.thanks :)