Theorem pssnssi 45679

Description: A proper subclass does not include the other class. (Contributed by Glauco Siliprandi, 26-Jun-2021.)

Hypothesis

Ref	Expression
pssnssi.1	⊢ 𝐴 ⊊ 𝐵

Assertion

Ref	Expression
pssnssi	⊢ ¬ 𝐵 ⊆ 𝐴

Proof of Theorem pssnssi

Step	Hyp	Ref	Expression
1		pssnssi.1	. . 3 ⊢ 𝐴 ⊊ 𝐵
2		dfpss3 4042	. . 3 ⊢ (𝐴 ⊊ 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ ¬ 𝐵 ⊆ 𝐴))
3	1, 2	mpbi 232	. 2 ⊢ (𝐴 ⊆ 𝐵 ∧ ¬ 𝐵 ⊆ 𝐴)
4	3	simpri 489	1 ⊢ ¬ 𝐵 ⊆ 𝐴

Syntax hints:  ¬ wn 3   ∧ wa 399   ⊆ wss 3904   ⊊ wpss 3905

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1815  ax-4 1829  ax-5 1930  ax-6 1987  ax-7 2028  ax-9 2152  ax-ext 2734

This theorem depends on definitions:  df-bi 209  df-an 400  df-ex 1800  df-cleq 2754  df-ne 2958  df-ss 3921  df-pss 3924

This theorem is referenced by:  nsssmfmbf  47353