Step
*
of Lemma
cat-square-commutes-comp
∀[C:SmallCategory]. ∀[x1,x2,x3,y1,y2,y3:cat-ob(C)]. ∀[x1_y1:cat-arrow(C) x1 y1]. ∀[x2_y2:cat-arrow(C) x2 y2].
∀[x3_y3:cat-arrow(C) x3 y3]. ∀[y1_y2:cat-arrow(C) y1 y2]. ∀[y2_y3:cat-arrow(C) y2 y3]. ∀[x1_x2:cat-arrow(C) x1 x2].
∀[x2_x3:cat-arrow(C) x2 x3].
(x1_y1 o cat-comp(C) y1 y2 y3 y1_y2 y2_y3 = cat-comp(C) x1 x2 x3 x1_x2 x2_x3 o x3_y3) supposing
(x1_y1 o y1_y2 = x1_x2 o x2_y2 and
x2_y2 o y2_y3 = x2_x3 o x3_y3)
BY
{ (Auto
THEN All (Unfold `cat-square-commutes`)
THEN (RW CatNormC 0 THENA Auto)
THEN (RWO "-1" 0 THENA Auto)
THEN (RWO "cat-comp-assoc" 0 THENA Auto)
THEN RWO "-2" 0
THEN Auto) }
Latex:
Latex:
\mforall{}[C:SmallCategory]. \mforall{}[x1,x2,x3,y1,y2,y3:cat-ob(C)]. \mforall{}[x1$_{y1}$:cat-arrow(C) x1 \000Cy1]. \mforall{}[x2$_{y2}$:cat-arrow(C)
x2
y2].
\mforall{}[x3$_{y3}$:cat-arrow(C) x3 y3]. \mforall{}[y1$_{y2}$:cat-arrow(C) y1\000C y2]. \mforall{}[y2$_{y3}$:cat-arrow(C) y2 y3].
\mforall{}[x1$_{x2}$:cat-arrow(C) x1 x2]. \mforall{}[x2$_{x3}$:cat-arrow(C) x2\000C x3].
(x1$_{y1}$ o cat-comp(C) y1 y2 y3 y1$_{y2}$ y2$_\mbackslash{}f\000Cf7by3}$ = cat-comp(C) x1 x2 x3 x1$_{x2}$ x2$_{x3}$ o\000C x3$_{y3}$) supposing
(x1$_{y1}$ o y1$_{y2}$ = x1$_{x2}$ \000Co x2$_{y2}$ and
x2$_{y2}$ o y2$_{y3}$ = x2$_{x3}$ o\000C x3$_{y3}$)
By
Latex:
(Auto
THEN All (Unfold `cat-square-commutes`)
THEN (RW CatNormC 0 THENA Auto)
THEN (RWO "-1" 0 THENA Auto)
THEN (RWO "cat-comp-assoc" 0 THENA Auto)
THEN RWO "-2" 0
THEN Auto)
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