完备联结词组
- $\{\neg,\lor,\land\}$
- $\{\neg,\to\}$
- $\{\Delta_1,\to\}$
- $\{\downarrow\}$
- $\{\uparrow\}$
与非词:$\uparrow$
- $\neg p \iff \neg (p\land p) \iff p\uparrow p$
- $p\land q\iff \neg\neg(p\land q) \iff \neg(p\uparrow q) \iff (p\uparrow q)\uparrow (p\uparrow q)$
- $p\lor q \iff \neg \neg(p\lor q) \iff \neg(\neg p\land \neg q)\iff (\neg p)\uparrow (\neg q) \iff (p\uparrow p)\uparrow (q\uparrow q)$
或非词:$\downarrow$
- $\neg p\iff \neg(p\lor p)\iff p\downarrow p$
- $\cdots$