An upper bound for the intermediate dimensions of Bedford–McMullen carpets

The intermediate dimensions of a set $\Lambda$, elsewhere denoted by $\dim\_{\theta}\Lambda$, interpolate between its Hausdorff and box using the parameter $\theta\in\[0,1]$. For Bedford–McMullen carpet $\Lambda$ with distinct dimensions, we show that $\dim\_{\theta}\Lambda$ is strictly less than dimension for every $\theta<1$. Moreover, derivative upper bound positive at $\theta=1$. This answers question Fraser; however, determining precise formula still remains challenging problem.