msc-thesis/thesis/diagrams/Model_Replacements.tex

\xymatrix{
	\cat{0} \ar[rr] \arcof[dr] &                     & X \\
	                           & X^{cof} \artfib[ur] &
}
\qquad
\xymatrix{
	X \ar[rr] \artcof[dr] &                    & \cat{1} \\
	                      & X^{fib} \arfib[ur] &
}