text/ncat.tex
changeset 721 3ae1a110873b
parent 719 76ad188dbe68
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   535 \end{axiom}
   535 \end{axiom}
   536 
   536 
   537 This axiom needs to be strengthened to force product morphisms to act as the identity.
   537 This axiom needs to be strengthened to force product morphisms to act as the identity.
   538 Let $X$ be an $n$-ball and $Y\sub\bd X$ be an $n{-}1$-ball.
   538 Let $X$ be an $n$-ball and $Y\sub\bd X$ be an $n{-}1$-ball.
   539 Let $J$ be a 1-ball (interval).
   539 Let $J$ be a 1-ball (interval).
   540 We have a collaring homeomorphism $s_{Y,J}: X\cup_Y (Y\times J) \to X$.
   540 Let $s_{Y,J}: X\cup_Y (Y\times J) \to X$ be a collaring homeomorphism
   541 (Here we use $Y\times J$ with boundary entirely pinched.)
   541 (see the end of \S\ref{ss:syst-o-fields}).
       
   542 Here we use $Y\times J$ with boundary entirely pinched.
   542 We define a map
   543 We define a map
   543 \begin{eqnarray*}
   544 \begin{eqnarray*}
   544 	\psi_{Y,J}: \cC(X) &\to& \cC(X) \\
   545 	\psi_{Y,J}: \cC(X) &\to& \cC(X) \\
   545 	a & \mapsto & s_{Y,J}(a \cup ((a|_Y)\times J)) .
   546 	a & \mapsto & s_{Y,J}(a \cup ((a|_Y)\times J)) .
   546 \end{eqnarray*}
   547 \end{eqnarray*}