Frown-inducing accusations have been flying in a trademark dispute between Wal-Mart and a company owned by a French family over US commercial rights to the ubiquitous yellow symbol for happiness. Both parties say they expect victory when the US Patent and Trademark Office rules on the case this summer. Wal-Mart, the world's largest retailer, says the yellow face has long personified its price-reducing policy, while SmileyWorld, the London-based company that first registered rights to the symbol decades ago, says its globally established business is at risk. "A prehistoric man probably invented the smiley face in some cave, but I certainly was the first to register it as a trademark," said Franklin Loufrani, 63, who says he initially registered the design with French trademark authorities in October 1971.