Nuprl Lemma : groupoid_inv
∀[G:Groupoid]
  ∀x,y:cat-ob(cat(G)). ∀f:cat-arrow(cat(G)) x y.
    (((cat-comp(cat(G)) x y x f groupoid-inv(G;x;y;f)) = (cat-id(cat(G)) x) ∈ (cat-arrow(cat(G)) x x))
    ∧ ((cat-comp(cat(G)) y x y groupoid-inv(G;x;y;f) f) = (cat-id(cat(G)) y) ∈ (cat-arrow(cat(G)) y y)))
Proof
Definitions occuring in Statement : 
groupoid-inv: groupoid-inv(G;x;y;x_y)
, 
groupoid-cat: cat(G)
, 
groupoid: Groupoid
, 
cat-comp: cat-comp(C)
, 
cat-id: cat-id(C)
, 
cat-arrow: cat-arrow(C)
, 
cat-ob: cat-ob(C)
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
and: P ∧ Q
, 
apply: f a
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
guard: {T}
, 
pi2: snd(t)
, 
groupoid-inv: groupoid-inv(G;x;y;x_y)
, 
pi1: fst(t)
, 
groupoid-cat: cat(G)
, 
groupoid: Groupoid
, 
cand: A c∧ B
, 
and: P ∧ Q
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
Lemmas referenced : 
groupoid_wf, 
cat-ob_wf, 
groupoid-cat_wf, 
cat-arrow_wf
Rules used in proof : 
because_Cache, 
axiomEquality, 
independent_pairEquality, 
dependent_functionElimination, 
lambdaEquality, 
hypothesisEquality, 
isectElimination, 
lemma_by_obid, 
applyEquality, 
independent_pairFormation, 
hypothesis, 
sqequalRule, 
rename, 
setElimination, 
thin, 
productElimination, 
sqequalHypSubstitution, 
lambdaFormation, 
cut, 
introduction, 
isect_memberFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}[G:Groupoid]
    \mforall{}x,y:cat-ob(cat(G)).  \mforall{}f:cat-arrow(cat(G))  x  y.
        (((cat-comp(cat(G))  x  y  x  f  groupoid-inv(G;x;y;f))  =  (cat-id(cat(G))  x))
        \mwedge{}  ((cat-comp(cat(G))  y  x  y  groupoid-inv(G;x;y;f)  f)  =  (cat-id(cat(G))  y)))
Date html generated:
2020_05_20-AM-07_55_16
Last ObjectModification:
2015_12_28-PM-02_23_11
Theory : small!categories
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