## AGM Postulates

Where $$K$$ is a belief state, $$K*A$$ represents the set of beliefs resulting from revising $$K$$ with new belief $$A$$.

• $$(K*1)$$ $$K*A$$ is closed under logical consequence.
• $$(K*2)$$ $$A$$ belongs to $$K*A$$.
• $$(K*3)$$ $$K*A$$ is a subset of the logical closure of $$K \cup \{A\}$$.
• $$(K*4)$$ If $$\neg A$$ does not belong to $$K$$, then the closure of $$K \cup \{A\}$$ is a subset of $$K*A$$.
• $$(K*5)$$ If $$K*A$$ is logically inconsistent, then either $$K$$ is inconsistent, or $$A$$ is.
• $$(K*6)$$ If $$A$$ and $$B$$ are logically equivalent, then K*A = K*B.
• $$(K*7)$$ $$K*(A \amp B)$$ is a subset of the logical closure of $$K*A \cup \{B\}$$.
• $$(K*8)$$ If $$\neg B$$ does not belong to $$K*A$$, then the logical closure of $$K*A \cup B$$ is a subset of $$K*(A \amp B)$$.