Critical and flow-critical snarks coincide

Over the past twenty years, critical and bicritical snarks have been appearing in literature various forms different contexts. Two main variants of criticality studied: with respect to non-existence a $3$-edge-colouring nowhere-zero $4$-flow. In this paper we show that these two kinds coincide, thereby completing previous partial results de Freitas et al. [Electron. Notes Discrete Math. 50 (2015), 199--204] Fiol [ arXiv:1702.07156v1 (2017)].