There's been some interesting research on that in airline fares. Airlines are pretty careful these days not to engage in any private collusion, but they have quite complex dances of intention-signalling via their fare raises/decreases, their pre-announcements of those fare changes, their press conferences at which they discuss what they might do in the future (and what actions by their competitors might influence them one way or another), etc.
The goal is to avoid price wars and maintain some sort of soft price-fixing, but to do it all entirely publicly without direct discussions. It's not as blatant anymore as it used to be, but at its height (until some 1990s lawsuits), they were effectively conveying things like price-floor offers, e.g. "if you don't cut on route X, I won't either", but via completely public press conferences that openly said things like, "we're not planning to cut fares in the next 3 months on this route, unless a fare cut by Competitor A or B out of these hubs forces us to".
The goal is to avoid price wars and maintain some sort of soft price-fixing, but to do it all entirely publicly without direct discussions. It's not as blatant anymore as it used to be, but at its height (until some 1990s lawsuits), they were effectively conveying things like price-floor offers, e.g. "if you don't cut on route X, I won't either", but via completely public press conferences that openly said things like, "we're not planning to cut fares in the next 3 months on this route, unless a fare cut by Competitor A or B out of these hubs forces us to".