MinNorm approximation of MaxEnt/MinDiv problems for probability tables Patrick Bogaert and Sarah Gengler UCL
Rebuilding probability tables UCL
Rebuilding probability tables • Limited number of samples Poor estimates UCL
Rebuilding probability tables • Limited number of samples Poor estimates • How to integrate experts opinion ? UCL
Rebuilding probability tables • Limited number of samples Poor estimates • How to integrate experts opinion ? Rewriting information as equality / inequality constraints UCL
Rebuilding probability tables • Limited number of samples Poor estimates • How to integrate experts opinion ? Rewriting information as equality / inequality constraints UCL
Rebuilding probability tables • Limited number of samples Poor estimates • How to integrate experts opinion ? Rewriting information as equality / inequality constraints • Equality constraints MaxEnt • Inequality constraints Minimum divergence ( MinDiv ) UCL
Rebuilding probability tables • Limited number of samples Poor estimates • How to integrate experts opinion ? Rewriting information as equality / inequality constraints • Equality constraints MaxEnt • Inequality constraints Minimum divergence ( MinDiv ) Need for an efficient methodology to rebuild probability tables from both equality and inequality constraints UCL
The MaxEnt problem UCL
The MaxEnt problem • Equality constraints UCL
The MaxEnt problem • Equality constraints • Entropy maximized subject to the equality constraints UCL
The MaxEnt problem • Equality constraints • Entropy maximized subject to the equality constraints UCL
The MaxEnt problem • Equality constraints • Entropy maximized subject to the equality constraints Sequence of MinNorm problems for solving the MaxEnt problem UCL
MinNorm as an approximation of MaxEnt UCL
MinNorm as an approximation of MaxEnt • Taylor series of ln p i around p i = k i UCL
MinNorm as an approximation of MaxEnt • Taylor series of ln p i around p i = k i • Truncating at degree one and summing over i UCL
MinNorm as an approximation of MaxEnt • Taylor series of ln p i around p i = k i • Truncating at degree one and summing over i • In particular, if k i = 1/n UCL
MinNorm as an approximation of MaxEnt • For any other choice of the k i ‘s, by completing the square UCL
MinNorm as an approximation of MaxEnt • For any other choice of the k i ‘s, by completing the square • Summing over i Where UCL
The MinDiv problem UCL
The MinDiv problem • Divergence or Kullback-Leibler distance UCL
The MinDiv problem • Divergence or Kullback-Leibler distance • Equality constraints = 0 Maximizing UCL
The MinDiv problem • Divergence or Kullback-Leibler distance • Equality constraints = 0 Maximizing UCL
The MinDiv problem • Divergence or Kullback-Leibler distance • Equality constraints = 0 Maximizing UCL
The MinDiv problem • Divergence or Kullback-Leibler distance • Equality constraints = 0 Maximizing Sequence of MinNorm problems for solving the MinDiv problem UCL
The MinDiv problem • Divergence or Kullback-Leibler distance • Equality constraints = 0 Maximizing Sequence of MinNorm problems for solving the MinDiv problem Both Equality and Inequality constraints can be processed together by MinNorm approximations UCL
MinNorm as an approximation of MinDiv UCL
MinNorm as an approximation of MinDiv • Taylor series around p i = k i and completing the square UCL
MinNorm as an approximation of MinDiv • Taylor series around p i = k i and completing the square • Summing over i Where UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping • Categorical data are found in a wide variety of applications UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping • Categorical data are found in a wide variety of applications • 90 % of variables collected in soil surveys are categorical • Soil drainage, an important criterion in rating soils for various uses UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Application in drainage classes mapping UCL
Integrating the lithological map : 4 cases UCL
Integrating the lithological map : 4 cases UCL
Integrating the lithological map : 4 cases UCL
Spatial prediction UCL
Integrating the lithological map : 4 cases UCL
Spatial prediction UCL
Integrating the lithological map : 4 cases UCL
Conclusions UCL
Conclusions UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Conclusions MinNorm Approximations UCL
Thank you for your attention UCL
References UCL
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