nLab
integration axiom

Contents

Idea

In the axiomatic formulation of differential geometry given by synthetic differential geometry the standard Kock-Lawvere axiom provides a notion of differentiation. In general this need not come with an inverse operation of integration. The additional integration axiom on a smooth topos does ensure this.

Definition

Definition

(integration axiom)

Let (𝒯,R) be a smooth topos and let the line object R be equipped with the structure of a partial order (R,) compatible with its ring structure (R,+,) in the obvious way.

Then for any a,bR write

[a,b]:={xRaxb}[a,b] := \{x \in R | a \leq x \leq b\}

We say that (𝒯,(R,+,,)) satisfies the integration axiom if for all such intervals, all functions on the interval arise uniquely as derivatives on functions on the interval that vanish at the left boundary:

fR [a,b]:! a fR [a,b]:( a f)(a)=0( a f)=f.\forall f \in R^{[a,b]} : \exists ! \int_a^{-} f \in R^{[a,b]} : (\int_a^{-} f)(a) = 0 \wedge (\int_a^{-} f)' = f \,.

… need to say more …

Examples

The axiom holds for all the smooth topos presented in MSIA, listed in appendix 2 there. See appendix 3 for the proof.

References

page 49 of

appendix 3 of

Revised on November 24, 2009 16:16:16 by david karapetyan? (204.140.153.10)