Nuprl Lemma : groupoid-left-cancellation
∀[G:Groupoid]. ∀[x,y,z:cat-ob(cat(G))]. ∀[a,b:cat-arrow(cat(G)) y z]. ∀[c:cat-arrow(cat(G)) x y].
  uiff((cat-comp(cat(G)) x y z c a) = (cat-comp(cat(G)) x y z c b) ∈ (cat-arrow(cat(G)) x z);a
  = b
  ∈ (cat-arrow(cat(G)) y z))
Proof
Definitions occuring in Statement : 
groupoid-cat: cat(G)
, 
groupoid: Groupoid
, 
cat-comp: cat-comp(C)
, 
cat-arrow: cat-arrow(C)
, 
cat-ob: cat-ob(C)
, 
uiff: uiff(P;Q)
, 
uall: ∀[x:A]. B[x]
, 
apply: f a
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
uimplies: b supposing a
, 
prop: ℙ
, 
true: True
, 
squash: ↓T
, 
all: ∀x:A. B[x]
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
implies: P 
⇒ Q
Lemmas referenced : 
equal_wf, 
cat-arrow_wf, 
groupoid-cat_wf, 
cat-comp_wf, 
and_wf, 
cat-ob_wf, 
groupoid_wf, 
groupoid-inv_wf, 
squash_wf, 
true_wf, 
cat-comp-assoc, 
groupoid_inv, 
cat-comp-ident, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
independent_pairFormation, 
hypothesis, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
applyEquality, 
hypothesisEquality, 
equalitySymmetry, 
dependent_set_memberEquality, 
applyLambdaEquality, 
setElimination, 
rename, 
productElimination, 
sqequalRule, 
independent_pairEquality, 
isect_memberEquality, 
axiomEquality, 
because_Cache, 
equalityTransitivity, 
natural_numberEquality, 
lambdaEquality, 
imageElimination, 
universeEquality, 
dependent_functionElimination, 
imageMemberEquality, 
baseClosed, 
independent_isectElimination, 
independent_functionElimination
Latex:
\mforall{}[G:Groupoid].  \mforall{}[x,y,z:cat-ob(cat(G))].  \mforall{}[a,b:cat-arrow(cat(G))  y  z].  \mforall{}[c:cat-arrow(cat(G))  x  y].
    uiff((cat-comp(cat(G))  x  y  z  c  a)  =  (cat-comp(cat(G))  x  y  z  c  b);a  =  b)
Date html generated:
2020_05_20-AM-07_55_52
Last ObjectModification:
2017_07_28-AM-09_20_14
Theory : small!categories
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