Glossary:Stability increase matrix

stability increase matrix (SInc matrix; SInc[])

the matrix that represents the function of interval/stability increase in Algorithm SM-17. For any item at any time, the increase in stability depends on:

1. current stability,
2. current retrievability, and
3. current item difficulty.

This function can be inspected using: Tools : Memory : 4D Graphs : Stability in SuperMemo. The SInc[] matrix can be considered an extension of the OF matrix (from older SuperMemos) into the dimension of retrievability. This means that the new Algorithm SM-17 can handle any repetition at any time, including freshly reviewed items, as well as long-neglected items. Retrievability is the dimension that reflects the time that has elapsed since the last repetition relative to the optimum interval