Table 2.

Priors for implausible losses

Probability	Loss type and molecular formulas
${10}^{-3}$	Implausible losses: ${\text{C}}_2\text{O}$, ${\text{C}}_4\text{O}$, ${\text{C}}_3{\text{H}}_2$, ${\text{C}}_5{\text{H}}_2$, ${\text{C}}_7{\text{H}}_2$
$\frac{1}{3^{rdbe}}$	Neutral losses with negative ring double bond equivalent RDBE
0.1	Nitrogen-only losses, carbon-only losses: for example, ${\text{N}}_5$ or ${\text{C}}_3$
1	All other neutral losses
0.9	Common radical losses: ${\text{H}}^{·}$, ${\text{O}}^{·}$, ${}^{·}\text{OH}$, ${}^{·}{\text{CH}}_3$, ${\text{CH}}_3{\text{O}}^{·}$, ${}^{·}{\text{C}}_3{\text{H}}_7$, ${}^{·}{\text{C}}_4{\text{H}}_9$, ${\text{C}}_6{\text{H}}_5{\text{O}}^{·}$
${10}^{-3}$	All other radical losses

For an edge (u, v) with loss $u-v$ let $P_{\text{loss-impl}}(u,v)$ be the prior for $u-v$ chosen according to this table. Expert knowledge and evaluation of FTs from SIRIUS² resulted in the implausible losses listed here [41]. These losses should only very rarely (if ever) occur in a FT, so we manually select reduced priors