| Format |
Representation |
Examples |
| Fuzzy |
undefined/marginal/complete, don't know/untrustworthy/marginal/full |
PGP's direc trust |
| Fuzzy |
very trustworthy/trustworthy/untrustworthy/very untrustworthy |
Ruth/Xu/Bhargava/Regnier's RT0 |
| General |
Lattice |
Moreton/Twigg |
| General |
Binary (yes, no) + possible supplementary information |
Trust management (Blaze/Feigenbaum's PolicyMaker and KeyNote) |
| Integer |
Virtual currency {0..infinity} |
Trustos in ubiquitous computing (http://www.trustos.com); maybe the Nuglets in mobile ad-hoc networks (http://www.lst.inf.ethz.ch/research/publications/publications/COM_MAG_2001/COM_MAG_2001.pdf) |
| Integer |
{-infinity..infinity} |
Slashdot.org's Karma; Ebay's feedback rating |
| Integer |
1-10 |
FOAF trust module - http://trust.mindswap.org/trustOnt.shtml |
| Integer |
{0..infinity} |
Chimaera (Tarah, Huitema); Free Haven (www.freehaven.net, Dingledine) direct and meta trust; Li Gong system and direct trust; PGP's parameters (number of agents); Advogato's trust metric |
| Integer |
{1..infinity} |
Ueli Maurer's deterministic trust |
| Integer |
{-1..4} |
Abdul-Rahman/Hailes; Poblano (www.jxta.org/docs/trust.pdf) |
| Logical |
Binary (true, false) |
Cryptographic logics (Burrows/Abadi/Needham' BAN, Gong/Needham/Yahalom's GNY, Syverson/van Oorschot's SvO); Freenet (www.freenetproject.org); Lars Rasmusson/Sverker Jansson; P. Venkat Rangan.; SPKI |
| Logical |
trust(trustor,trustee,action,level) where level is in {-100;100} |
Grandison/Sloman's SULTAN |
| Logical |
trustBL(trustor,service,trustee,,depth,blacklist) where depth is in {0..infinity} + {*} (* for ) |
Giorgini/Massaci/Mylopoulos/Zannone |
| Logical |
formulas |
Demolombe/Jones logics; Walt Teh-Ming Yao's Fidelis |
| Matrix |
Table |
Yao-Hua Tan |
| Real |
[0;1] |
Ueli Maurer's probabilistic trust; Neurogrid (www.neurogrid.net, Samuel Joseph); Sierra's (sierra.openprivacy.org, OpenPrivacy) System trust; Castelfranchi/Falcone/Pezzulo's trustfulness |
| Real |
[0;1[ |
BBK (Beth, Borchedring, Klein) direct trust |
| Real |
]0;1[ |
IST (Jamil, Sadri, Shiri) |
| Real |
[-1;1] |
Marsch (http://citeseer.ist.psu.edu/marsh94formalising.html); Sierra's (sierra.openprivacy.org, OpenPrivacy) interpersonal and self trust |
| Vector |
Tuple (each component in [0;1]) |
Josang's opinions (belief/disbelief/uncertainty/atomicity); Narendar Shankar/William A. Arbaugh; Golbeck/Hendler/Parsia (minimum, maximum, and weighted average trust); SECURE (support, inconclusive, contradict) |
| Vector |
Emotional Bank Account (EBA) Tuple of 3 fields in a given virtual currency (amount of money paid by the trustee in terms of actions; money lost due to these actions; some money, which is not yet known to be gained or lost) |
Trustee's EBA(100,12,4): the trustor has gained 100 trustos from this trustee, lost 12 trustos and 4 trustos are still not processed (http://www.cs.tcd.ie/publications/tech-reports/reports.04/TCD-CS-2004-37.pdf) ; the term Emotional Bank Account is from Stephen Covey's 7 habits of highly effective people |
| Vector |
Tuple (number of positive outcomes, number of negative outcomes, number of unknown outcomes) |
Number of positive previous experiences of an entity with another that can be transferred between two entities according to a specific process, for example, Trust Transfer, which makes the metric resistant to Sybil attacks |
