Zimbabwe's President Robert Mugabe appeared in public on Friday for the first time since the army took charge this week, as the ruling party made plans to force him to step down after more than three decades in power.The president, who is 93, opened a graduation ceremony at Zimbabwe Open University in Harare. He wore blue and yellow academic robes and a mortar board hat and appeared to fall asleep in his chair as his eyes closed and his head lolled.Mugabe led the country's liberation struggle and has dominated its politics since independence in 1980 but the army takeover signals the collapse of his authority even though he says he is still in charge. A senior member of the ZANU-PF ruling party said it wanted him gone."If he becomes stubborn, we will arrange for him to be fired on Sunday," the source said. "When that is done, it's impeachment on Tuesday."In contrast, the military said in a statement on national television it was "engaging" with Mugabe. It referred to him as Commander in Chief and said it would announce an outcome as soon as possible.