Discovering a Spatial Genotype in Edo Middle–Lower-Class Samurai Residences: A Space Syntax Analysis of Boundary-Regulation Logic as a Configurational Layout Principle

This study examines whether the spatial configurations observed in Edo middle–lower-class samurai residences can be interpreted as a recurrent spatial genotype. Previous studies have repeatedly identified the structural centrality of the Ura (裏・ウチ: family-living domain), but have not examined whether this tendency co-occurs with the consistently high control role of the entry court as a recurrent boundary-control anchor. A space syntax analysis of 77 Edo middle–lower-class samurai residences yields a mean Base Difference Factor (BDF) of 0.86, indicating a relatively dispersed integration distribution rather than a concentration around a single dominant space. Accordingly, a conventional single-maximum integration value classification produces 16 apparent single-maximum types without a dominant pattern. By combining the top 10% upper-integration-band criterion, a justified graph distribution analysis, and a control value analysis, this study identifies the entry court as a recurrent boundary-control anchor coexisting with Ura family-living integration centrality. This recurrent relationship is interpreted as a Boundary-Regulating Genotype. The genotype is expressed in three configurational states. In the Double state (24 cases), the boundary/access zone and the Ura family-living domain are both involved in the upper integration distribution. In the Deep state (42 cases), the upper integration field is oriented toward the Ura domain, while the entry court remains a boundary-control anchor. In the Shallow state (11 cases), integration shifts toward boundary/access spaces. This relational genotype provides a basis for reconsidering Sekkyaku-honi as a boundary-centered access-regulation logic linking the public road, entry court, Omote (表: formal reception) domain, and Ura family-living domain.