Abstract: A virtual image display apparatus includes a housing having a first housing part and a second housing part. The first housing part is located on a side facing in a first direction. The second housing part is located on a side facing in a second direction being opposite to the first direction. A composite wall is located at the housing on a side facing in a third direction being perpendicular to the first direction. The composite wall includes a first front wall portion and a second front wall portion. The first front wall portion is extended from the first housing part. The second front wall portion is extended from the second housing part. The first and second front wall portions have an interference avoidance structure that avoids interference when the first and second front wall portions approach each other by receiving a load.

Abstract: A feature amount selection device includes a feature amount data acquisition unit that acquires feature amount data including a set of values of a plurality of feature amounts for a sample, for each of a plurality of the samples, a principal component analysis unit that performs, on the feature amount data, principal component analysis in a sample space that is a collection of the plurality of feature amounts of a set of values for each of the plurality of the samples of the feature amounts, and a feature amount selection unit that selects a feature amount from among the plurality of the feature amounts based on a result of the principal component analysis performed by the principal component analysis unit.