Method execute

src/nlr/DeepPolySigmoidElement.cpp:35–103

}

void DeepPolySigmoidElement::execute(
    const Map<unsigned, DeepPolyElement *> &deepPolyElementsBefore )
{
    log( "Executing..." );
    ASSERT( hasPredecessor() );
    allocateMemory();

    // Update the symbolic and concrete upper- and lower- bounds
    // of each neuron
    for ( unsigned i = 0; i < _size; ++i )
    {
        NeuronIndex sourceIndex = *( _layer->getActivationSources( i ).begin() );
        DeepPolyElement *predecessor = deepPolyElementsBefore[sourceIndex._layer];
        double sourceLb = predecessor->getLowerBound( sourceIndex._neuron );
        double sourceUb = predecessor->getUpperBound( sourceIndex._neuron );

        _ub[i] = SigmoidConstraint::sigmoid( sourceUb );
        _lb[i] = SigmoidConstraint::sigmoid( sourceLb );

        if ( sourceUb == sourceLb )
        {
            _symbolicUb[i] = 0;
            _symbolicUpperBias[i] = _ub[i];
            _symbolicLb[i] = 0;
            _symbolicLowerBias[i] = _lb[i];
        }
        else
        {
            double lambda = ( _ub[i] - _lb[i] ) / ( sourceUb - sourceLb );
            double lambdaPrime = std::min( SigmoidConstraint::sigmoidDerivative( sourceLb ),
                                           SigmoidConstraint::sigmoidDerivative( sourceUb ) );

            // update lower bound
            if ( FloatUtils::isPositive( sourceLb ) )
            {
                _symbolicLb[i] = lambda;
                _symbolicLowerBias[i] = SigmoidConstraint::sigmoid( sourceLb ) - lambda * sourceLb;
            }
            else
            {
                _symbolicLb[i] = lambdaPrime;
                _symbolicLowerBias[i] =
                    SigmoidConstraint::sigmoid( sourceLb ) - lambdaPrime * sourceLb;
            }

            // update upper bound
            if ( !FloatUtils::isPositive( sourceUb ) )
            {
                _symbolicUb[i] = lambda;
                _symbolicUpperBias[i] = SigmoidConstraint::sigmoid( sourceUb ) - lambda * sourceUb;
            }
            else
            {
                _symbolicUb[i] = lambdaPrime;
                _symbolicUpperBias[i] =
                    SigmoidConstraint::sigmoid( sourceUb ) - lambdaPrime * sourceUb;
            }
        }