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. Author manuscript; available in PMC: 2016 Sep 26.
Published in final edited form as: Nat Commun. 2014 Oct 31;5:5277. doi: 10.1038/ncomms6277

Figure 4.

Figure 4

Constructing a Directed Acyclic Graph (DAG) in the case of two “amino acids” with real masses 2.012 and 2.996. Assume that only singly-charged b-ion with a real of f set 1.008 contributes to the scoring. The spectrum S is converted into S′ by shifting each peak by 1.008 to the left. Each arrowed line in S′ represents a pair of peaks separated approximately by 2 Da (blue) or 3 Da (red) that form a duo (solid) or does not form a duo (dashed) for a fragment mass tolerance 0.01 Da. A DAG G is constructed from S′. The number in the vertex represents its label. The color of the edge represents its label (0 for dashed grey and 1 for solid black).