ChatGPT and its owners must have hoped it was a hallucination. But DeepSeek is very real. The emergence of a new Chinese-made competitor to ChatGPT wiped $1tn off the leading tech index in the US this week after its owner said it rivalled its peers in performance and was developed with fewer resources. It means America’s dominance of the booming artificial intelligence market is under threat. But it also presents another option for consumers who have an array of virtual assistants to choose from. The Guardian tried out the leading chatbots, including DeepSeek, with the assistance of an expert from...