. "Any process that activates or increases the frequency, rate or extent of heterochromatin formation." . . . "positive regulation of heterochromatin assembly" . "activation of heterochromatin formation" . "positive regulation of heterochromatin formation" . "stimulation of heterochromatin formation" . "up regulation of heterochromatin formation" . "up-regulation of heterochromatin formation" . "upregulation of heterochromatin formation" . . . . . . . . . . . . . . . . . . . . .