Posted on November 4, 2016 by Charles V. Bagli in The New York Times The New York Times, By Charles V. Bagli As the number of New Yorkers living in shelters continues to rise, the administration of Mayor Bill de Blasio has told real estate developers they must make room for the homeless in buildings that received tax breaks under a program designed to increase the stock of affordable housing. Under the program, known as 421-a, 20 percent of apartments in buildings whose units were otherwise market rate had to be set aside for low- and moderate-income tenants. Half those apartments were to be distributed through individual lotteries; the other half were to go to those covered by so-called community preferences, a group that can include local residents, older men and women, disabled people or military veterans.