Farkas - type results for convex and non - convex inequality systems
As the title already suggests the aim of the present work is to present Farkas - type results for inequality systems involving convex and/or non - convex functions. To be able to give the desired results, we treat optimization problems which involve convex and composed convex functions or non - conv...
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| Format: | Doctoral Thesis |
| Language: | English |
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Universitätsbibliothek Chemnitz
2008
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| Online Access: | http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200800075 http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200800075 http://www.qucosa.de/fileadmin/data/qucosa/documents/5533/data/ibhodrea_thesis.pdf http://www.qucosa.de/fileadmin/data/qucosa/documents/5533/20080007.txt |
| Summary: | As the title already suggests the aim of the present work is to present Farkas -
type results for inequality systems involving convex and/or non - convex functions.
To be able to give the desired results, we treat optimization problems which involve
convex and composed convex functions or non - convex functions like DC functions
or fractions.
To be able to use the fruitful Fenchel - Lagrange duality approach, to the primal
problem we attach an equivalent problem which is a convex optimization problem.
After giving a dual problem to the problem we initially treat, we provide weak
necessary conditions which secure strong duality, i.e., the case when the optimal
objective value of the primal problem coincides with the optimal objective value of
the dual problem and, moreover, the dual problem has an optimal solution.
Further, two ideas are followed. Firstly, using the weak and strong duality
between the primal problem and the dual problem, we are able to give necessary
and sufficient optimality conditions for the optimal solutions of the primal problem.
Secondly, provided that no duality gap lies between the primal problem and its
Fenchel - Lagrange - type dual we are able to demonstrate some Farkas - type
results and thus to underline once more the connections between the theorems of
the alternative and the theory of duality. One statement of the above mentioned
Farkas - type results is characterized using only epigraphs of functions.
We conclude our investigations by providing necessary and sufficient optimality
conditions for a multiobjective programming problem involving composed convex
functions. Using the well-known linear scalarization to the primal multiobjective
program a family of scalar optimization problems is attached. Further to each of
these scalar problems the Fenchel - Lagrange dual problem is determined. Making
use of the weak and strong duality between the scalarized problem and its dual the
desired optimality conditions are proved. Moreover, the way the dual problem of
the scalarized problem looks like gives us an idea about how to construct a vector
dual problem to the initial one. Further weak and strong vector duality assertions
are provided. |
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