Theorem 4nprm

Description: 4 is not a prime number. (Contributed by Paul Chapman, 22-Jun-2011) (Proof shortened by Mario Carneiro, 18-Feb-2014)

	Ref	Expression
Assertion	4nprm	$$⊢\neg 4\in \mathbb{P}$$

Proof

Step	Hyp	Ref	Expression
1		2nn	$$⊢2\in \mathbb{N}$$
2		1lt2	$$⊢1<2$$
3		2t2e4	$$⊢2\cdot 2=4$$
4	1 1 2 2 3	nprmi	$$⊢\neg 4\in \mathbb{P}$$