Random chance performance for Pairwise Accuracy in "Ties Matter: Meta-Evaluating Modern Metrics with Pairwise Accuracy and Tie Calibration"

[linzhiqiu]

I was wondering if there are formulas to calculate the random chance performance (if the metric assigns random scores) for the proposed pairwise accuracy metric in "Ties Matter: Meta-Evaluating Modern Metrics with Pairwise Accuracy and Tie Calibration". Or is it not meaningful to calculate this?