In philosophy, specifically metaphysics, mereology is the study of parthood relationships. In mathematics and formal logic, wellfoundedness prohibits ${\displaystyle \cdots <x<\cdots <x<\cdots }$ for any x.

Thus non-wellfounded mereology treats topologically circular, cyclical, repetitive, or other eventual self-containment.

More formally, non-wellfounded partial orders may exhibit ${\displaystyle \cdots <x<\cdots <x<\cdots }$ for some x whereas well-founded orders prohibit that.

See also

• Aczel's anti-foundation axiom
• Peter Aczel
• John Barwise
• Steve Awodey
• Dana Scott

External links

• "Non-wellfounded Set Theory" entry by Lawrence S. Moss in the Stanford Encyclopedia of Philosophy, 2017-01-05