~~o~~~~~~~~~o~~~~~~~~~o

DARM.  Note 18

o~~~~~~~~~o~~~~~~~~~o~~~~~~~~~o~~~~~~~~~o~~~~~~~~~o

| 2.2.  Submanifolds, Immersions, Submersions (concl.)
|
| Proposition 2.6.  Assume that each P_i admits a manifold structure (compatible
|
|                   with its topology) such that these maps are morphisms,
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|                   making P_i into a fiber product of f_i and g_i.
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|                   Then P, with its natural projections,
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|                   is a fiber product of f and g.
|
| To prove the abo