Chinese artificial intelligence (AI) companies are racking up huge advertising bills, according to figures from a marketing consultancy, as firms search for any possible edge in a highly competitive market.In the third quarter alone, AI firms – from high-flying start-ups such as Moonshot AI and Zhipu AI to tech giants such as ByteDance and Alibaba Group Holding – have spent more than 500 million yuan (US$70.2 million) to promote chatbots and other AI applications, according to marketing analytic...