3 ideas
9117 | The smallest heap has four objects: three on the bottom, one on the top [Hart,WD, by Sorensen] |
17447 | Parsons says counting is tagging as first, second, third..., and converting the last to a cardinal [Parsons,C, by Heck] |
14367 | An explanation is a causal graph [Woodward,J, by Strevens] |