The terms “post-rock” and “math-rock” can leave many eyes rolled firmly back in one’s skull, or just leave some scratching their heads. Although the genres have long been fleshed out with artists such as Explosions in the Sky, Godspeed You! Black Emperor, Mogwai, And So I Watch You From Afar and TTNG, lingering questions remain. Clearly there’s texture, expanse, intricate time signatures, and often an overhanging emotional heft, but otherwise, it seems to have an anything-goes, gung-ho spirit more than most genres. Dublin four-piece Arms That Fit Like Legs do little to cement any working definitions. Since releasing their self-titled debut EP in…