Nuprl Lemma : flip_twice
∀[k:ℤ]. ∀[x,y,i:ℕk].  (((y, x) ((y, x) i)) = i ∈ ℤ)
Proof
Definitions occuring in Statement : 
flip: (i, j)
, 
int_seg: {i..j-}
, 
uall: ∀[x:A]. B[x]
, 
apply: f a
, 
natural_number: $n
, 
int: ℤ
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
compose: f o g
, 
int_seg: {i..j-}
, 
true: True
, 
squash: ↓T
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
rev_implies: P 
⇐ Q
, 
implies: P 
⇒ Q
Lemmas referenced : 
int_seg_wf, 
equal_wf, 
squash_wf, 
true_wf, 
flip_inverse, 
subtype_rel_self, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
hypothesis, 
Error :inhabitedIsType, 
hypothesisEquality, 
sqequalRule, 
sqequalHypSubstitution, 
isect_memberEquality, 
isectElimination, 
thin, 
axiomEquality, 
extract_by_obid, 
natural_numberEquality, 
because_Cache, 
Error :universeIsType, 
intEquality, 
setElimination, 
rename, 
applyEquality, 
lambdaEquality, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
universeEquality, 
imageMemberEquality, 
baseClosed, 
instantiate, 
independent_isectElimination, 
productElimination, 
independent_functionElimination
Latex:
\mforall{}[k:\mBbbZ{}].  \mforall{}[x,y,i:\mBbbN{}k].    (((y,  x)  ((y,  x)  i))  =  i)
Date html generated:
2019_06_20-PM-01_36_14
Last ObjectModification:
2018_09_26-PM-05_52_32
Theory : list_1
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