Metric
From Speedsolving.com Wiki
A metric (more specifically, move count metric or turn metric) is a convention for counting moves. The same sequence of moves can have different move counts depending on the metric used.
Summary of different metrics
For more details, see the respective articles.
- HTM; Half Turn Metric (or Face Turn Metric): Any face turn of any angle counts as 1 turn.
- QTM; Quarter Turn Metric: Only quarter (90-degree) face turns count as 1 turn.
- STM; Slice Turn Metric: Any turn of any layer, by any angle, counts as 1 turn.
- QSTM; Quarter Slice Turn Metric: Only quarter turns of any layer, by any angle, counts as 1 turn.
- ATM; Axial Turn Metric: Any movement within the same axis counts as 1 turn.
- ETM; Execution Turn Metric: Any perceived movement counts as 1 turn.
- BTM; Block Turn Metric: A metric for measuring movecounts on Bigcubes
Uses
HTM has been used to. For example, God's number is known to be 20 in HTM. From a mathematical standpoint, however, QTM seems a more natural choice; half-turns are visibly redundant as generators.
Debate over metric in FMC
WCA uses HTM in FMC. There has been a number of debates arguing for different metrics.
See also
Links
- (Speedsolving Forum) Move count metrics for big cubes - standards and preferences
