It is rare for an ex-neo-Nazi skinhead to sit down with…former Islamist extremists…It is rarer still for them to be joined by a survivor of the terrorist attacks on London in 2005. But…they all shared a stage…at a conference to discuss violent extremism…The meeting was arranged by Google Ideas, the internet giant’s new think-tank…Google, says Eric Schmidt, its chairman, is trying to come up with ideas to make the world a better place…Combating the rise of violent extremism has preoccupied governments for a decade…Predictably, Jared Cohen, who heads Google Ideas, is keen to promote the role of technology in this battle. Suggestions from those at the conference included an online encyclopedia to debunk the narratives of extremist groups; a WikiKoran to offer different interpretations of scripture and encourage debate; and a video game set in the gang world where the winning strategy would require getting characters to abandon their thuggish ways.