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spec: In order to explain it , he invented the population theory , which is just as senseless - - indeed even more senseless than the contradiction of coexisting wealth and poverty . For excavations in which employees may be exposed to unstable ground , qualified personnel using practices that are compatible with standards required by a registered architect , a registered professional engineer or other duly licensed or recognized authority will design support systems such as piling , cribbing , bracing and shoring that meet accepted engineering requirements to contain the walls .