One form of defense to keeping Ethos a credible and safe place is in the form of limiting the number of invitations in Ethos.
Another way of defending Ethos' network of credible users is to create a bonding period with new users and whoever invited them. This ensures that users opt more towards inviting credible people over those who are untrusted.
The bonding period is currently for 180 days(Previously 90 days before EIP-10.1). During this bonding period, the inviter takes on 20% of the impact of the user they invited's net credibility score change with a maximum downside of -120 and upside of +80.
As an example, if you invite someone that starts with a credibility score of 1200 (Neutral) and during those 180 days they gain +400 credibility score, you'll earn +80 credibility score for yourself. This reward encourages users to invite other trustworthy people.
If during those 180 days they lose 800 credibility score, you'll lose 160 credibility score for yourself, to discourage people inviting untrustworthy people.
Once the bonding period has completed, the scores then move independently from one another.
EIP-10.1: Revision to Invitation Bond Calculation
In EIP-10.1 we made some changes to how the bonding system works so people who brought in high quality users would be rewarded and people who invited bad actors to get more score deducted.
In summary:
This proposal updates the calculation method for the Invitation Bond component of the Ethos scoring algorithm. Instead of using a weighted average across all accepted invitations, the new approach will only take into account the scores of the top 2 and bottom 2 accepted invitations.
If you would like to read more about EIP-10.1 click here.