 In relation to housing projects with participation Herman Hertzberger used the terms "Architecture as half-product" or "Open structures" and Alejandro Aravena the terms "Participatory design process", "Incremental housing" and "Half-houses".Structuralism in architecture and urban planning had its origins in the Congrès International d'Architecture Moderne (CIAM) after World War II.Between 1928 and 1959, the CIAM was an important platform for the discussion of architecture and urbanism.