Before revision:  In addition , we show how to turn a repeat-free (elastic ) founder graph into a Wheeler graph in polynomial time . Furthermore, we show that a property such as repeat-freeness is essential for indexability. In particular, we show that unless the Strong Exponential Time Hypothesis (SETH) fails, one cannot build an index on an elastic founder graph in polynomial time to support fast queries .
After revision:  In addition , we show how to turn a repeat-free (elastic ) founder graph into a Wheeler graph in polynomial time .