Samsung said Wednesday it was rolling out new voice-assistant features to challenge its U.S. rivals' dominance in AI. At its developer conference, where the company is also expected to unveil its first foldable smartphone, the company said it was fully opening its virtual assistant, called Bixby, to third-party developers and businesses for the first time. The move may help the company challenge incumbent players Amazon's Alexa, Apple's Siri, and Google's Assistant.Much of the assistant market is yet to be tapped, and it is the right time for developers to embrace Bixby, an executive said. The company said it is offering a no-trade off set of tools (what it calls Bixby Developer Studio) to developers to make use of Bixby. It's the first time any company is offering the full suite of tools that it uses to make its assistant to developers, the company said.