Nuprl Lemma : cat-isomorphic_weakening
∀C:SmallCategory. ∀x,y:cat-ob(C).  cat-isomorphic(C;x;y) supposing x = y ∈ cat-ob(C)
Proof
Definitions occuring in Statement : 
cat-isomorphic: cat-isomorphic(C;x;y), 
cat-ob: cat-ob(C), 
small-category: SmallCategory, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
uimplies: b supposing a, 
member: t ∈ T, 
cat-isomorphic: cat-isomorphic(C;x;y), 
exists: ∃x:A. B[x], 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
squash: ↓T, 
prop: ℙ, 
true: True, 
guard: {T}, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q
Lemmas referenced : 
cat-id_wf, 
subtype_rel_self, 
cat-arrow_wf, 
subtype_rel_wf, 
cat-isomorphism_wf, 
squash_wf, 
true_wf, 
iff_weakening_equal, 
cat-id-isomorphism, 
equal_wf, 
cat-ob_wf, 
small-category_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
isect_memberFormation, 
cut, 
introduction, 
axiomEquality, 
hypothesis, 
thin, 
rename, 
dependent_pairFormation, 
applyEquality, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
hyp_replacement, 
equalitySymmetry, 
applyLambdaEquality, 
sqequalRule, 
lambdaEquality, 
imageElimination, 
equalityTransitivity, 
because_Cache, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
universeEquality, 
independent_isectElimination, 
productElimination, 
independent_functionElimination, 
dependent_functionElimination
Latex:
\mforall{}C:SmallCategory.  \mforall{}x,y:cat-ob(C).    cat-isomorphic(C;x;y)  supposing  x  =  y
 Date html generated: 
2020_05_20-AM-07_50_17
 Last ObjectModification: 
2017_01_10-PM-06_12_06
Theory : small!categories
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