Whenever a cycle like this arises in a game, the mathematician John Nash showed that there exists what's known as an unexploitable mixed strategy. Tom should bluff some fraction of the time that he has Q♠, whilst John should call to catch a bluff some fraction of the time that he has K♠. The strategy is called unexploitable because neither player can improve their win rate by choosing a different strategy, so neither has an incentive to deviate from it. Below I will explain the mathematics that leads us to conclude that the unexploitable mixed strategy for Tom is to bluff 1/3 of the time that he is dealt Q♠ and for John to call 1/3 of the time that he is dealt K♠. If either player uses this strategy, Tom makes a profit in the long run of about 5.5p per hand. The game is skewed in Tom's favour since he has the option of checking and showing down K♠, an option that John does not have. The game can be made fair by forcing John and Tom to alternate roles from hand to hand.