### Melting temperature deviation

To ensure that primers share similar melting temperatures, a threshold ΔTm on the maximal allowed difference in melting temperatures between any two primers in the set can be applied. This criterion is important for finding an optimal primer set, where only primers with similar melting temperatures should be present. Given a candidate primer p and the current optimal set of primers P, p is only added to P if

max i |Tm(Pi) - Tm(p)| < ΔTm