New posts in Alternative Set Theories

Infinite, totally ordered and well ordered sets

Relative consistency of $\mathsf{ZFC}-$Ext$+\neg$Ext+"every set has a unique powerset"

How badly does foundation fail in NF(etc.)?

Can one-element set be considered equal to its element?

How much maths can we do in NF(U)?

Alternative set theories

Why use ZF over NFU?