  This paper proposes strategies to improve the IOTA tangle in terms of
resilience to splitting attacks. Our contribution is two fold. First, we define
the notion of confidence fairness for tips selection algorithms to guarantee
the first approval for all honest tips. Then, we analyze IOTA-tangle from the
point of view of confidence fairness and identify its drawbacks. Second, we
propose a new selection mechanism, G-IOTA, that targets to protect tips left
behind. G-IOTA therefore has a good confidence fairness. G-IOTA lets honest
transactions increase their confidence efficiently. Furthermore, G-IOTA
includes an incentive mechanism for users who respect the algorithm and
punishes conflicting transactions. Additionally, G-IOTA provides a mutual
supervision mechanism that reduces the benefits of speculative and lazy
behaviours.
