Definition df-stab 821

Description: Propositions where a double-negative can be removed are called stable. See Chapter 2 [Moschovakis] p. 2.

Our notation for stability is a connective STAB which we place before the formula in question. For example, STAB 𝑥 = 𝑦 corresponds to "𝑥 = 𝑦 is stable".

(Contributed by David A. Wheeler, 13-Aug-2018.)

Assertion

Ref	Expression
df-stab	⊢ (STAB 𝜑 ↔ (¬ ¬ 𝜑 → 𝜑))

Detailed syntax breakdown of Definition df-stab

Step	Hyp	Ref	Expression
1		wph	. . 3 wff 𝜑
2	1	wstab 820	. 2 wff STAB 𝜑
3	1	wn 3	. . . 4 wff ¬ 𝜑
4	3	wn 3	. . 3 wff ¬ ¬ 𝜑
5	4, 1	wi 4	. 2 wff (¬ ¬ 𝜑 → 𝜑)
6	2, 5	wb 104	1 wff (STAB 𝜑 ↔ (¬ ¬ 𝜑 → 𝜑))

This definition is referenced by:  stbid  822  stabnot  823  dcstab  834  stdcndc  835  stdcndcOLD  836  stdcn  837  const  842  imanst  878  ddifstab  3253  bj-trst  13580  bj-fast  13582  bj-nnbist  13585  bj-stim  13587  bj-stan  13588  bj-stand  13589  bj-stal  13590  bj-pm2.18st  13591  bj-con1st  13592  bdstab  13669  exmid1stab  13840  subctctexmid  13841