How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Smooth families and path components in the weak topology
Statement
Assume . Let be compact, smooth, and a compact parameter pair. Every continuous -family of smooth maps with adjoint smooth near is homotopic relative to to a smooth family. For the following immersion-family assertions assume . If its values are genuine immersions, the homotopy remains genuine; for formal immersions, the hypothesis concerns both adjoint maps and the homotopy remains formal. Path components of are regular homotopy classes. Based homotopy sets defined by spheres or cubes agree with those defined by smooth families, for both genuine and formal immersion spaces. Formal-family smoothing itself does not require compact .
Facts & Assumptions
Given: , compact smooth , smooth , a compact parameter pair , and a continuous family whose relevant adjoint data are smooth near ; for immersion families, .
Smooth families are weakly continuous, and joint source-jet continuity characterises weak continuity (Joint jet continuity characterises the weak smooth topology, Compact parameter pairs and relative families).
A formal family smooth near can be smoothed relative to a neighbourhood of through formal families, without requiring holonomicity there (Smoothing continuous families of formal immersions).
A genuine family smooth near can be smoothed relative to through genuine families; every continuous path can be smoothed relative to both endpoints (Smoothing continuous families of genuine immersions).
Regular homotopy means a jointly smooth path with immersion slices (Regular homotopy of immersions); homotopies relative to a subset fix its values throughout (Homotopies of continuous maps, homotopies relative to a subspace, and path homotopies relative to the endpoints).
Proof
Apply [L1] for formal data and [L2] for genuine data. If an open neighbourhood of rather than a product neighbourhood is given, compactness of and a finite product-neighbourhood cover of each give a parameter neighbourhood of on which all the data are smooth; the union over gives the required open . For general smooth maps repeat the construction of [L2] with the immersion requirement removed: compactness gives a permitted value-error keeping interpolation in the tubular domain, parameter convolution gives the smooth approximant, and the cutoff fixes a neighbourhood of . No reference family, logarithm or complete metric is needed.
By the endpoint-preserving conclusion of [L2], every continuous path in joins regularly homotopic immersions. Conversely a regular homotopy is a continuous path by [F1]. This proves the component assertion with the prescribed endpoints unchanged.
For a based cubical family, precompose each coordinate with a smooth self-map of equal to zero near zero and one near one. This precomposition is homotopic to the identity by straight interpolation, preserves the boundary, and makes the family equal to its basepoint on a neighbourhood of the boundary. For a based spherical family, use a smooth self-map of the sphere homotopic to the identity relative to the basepoint and constant on a small neighbourhood of it: in a coordinate ball about that point replace the radial coordinate by a smooth function which is zero near zero and equals near the edge; extend by the identity outside the ball. Radial interpolation supplies the stated homotopy. These precompositions give smooth adjoint data near the relative set because the basepoint datum is a fixed smooth map or fixed smooth formal pair. Step 1.1 then supplies based smooth representatives.
To compare homotopies between smooth representatives, reparametrize the homotopy interval to be constant near its ends, and precompose the sphere or cube coordinates as in step 2.2. The resulting adjoint is smooth near the union of the end faces and the basepoint or boundary cylinder. Smooth it relative to that union using step 1.1. Its endpoints are the precomposed smooth representatives; each original smooth representative is joined to its precomposition by the smooth radial or cubical interpolation. Concatenating with smooth reparametrizations constant near the joining times gives a smooth based homotopy between the original representatives. Thus smooth representatives have exactly the same based homotopy classes as continuous ones.
Depends on
- Compact parameter pairs and relative families
- Space of immersions and space of formal immersions
- Regular homotopy of immersions
- Smoothing continuous families of formal immersions
- Smoothing continuous families of genuine immersions
- Joint jet continuity characterises the weak smooth topology
- The weak compact-open C-infinity topology on mapping spaces
- Open cover, subcover, and compact topological space; a compact subset is a subspace that is compact in its own right
- The exponential law: for a locally compact metric $X$ and any spaces $Z$ and $Y$, transposition is a bijection between $C(X \times Z, Y)$ and $C(Z, C(X,Y))$ with the compact-open topology
- The compact-open topology on $C(X,Y)$ for a metric domain $X$, with subbasis $S(K,V) = \{f : f[K] \subseteq V\}$
- Smooth families of maps and their evaluation maps
- Homotopies of continuous maps, homotopies relative to a subspace, and path homotopies relative to the endpoints
- The Axiom of Countable Choice ($\mathrm{AC}_\omega$)
Used by
Dependency tree · two levels
69 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- Andrew Ranicki, Algebraic and Geometric Surgery, Ch. 7 §7.4 “The Smale–Hirsch classification of immersions”, printed pp. 142–146 (Theorem 7.35, Proposition 7.39) (standard reference, not scraped)
- John Francis, The h-Principle, Lecture 3: Immersion theory (notes by O. Gwilliam), PDF pp. 1–4: Proposition 2.2 (disk), Definition 2.5 (Serre fibration), Definition 2.6 and Proposition 2.7 (flexible sheaves) (standard reference, not scraped)
- Ralph L. Cohen, Bundles, Manifolds, and Homotopy, Ch. 7 §2 “Obstructions to the existence of embeddings and immersions, the Hirsch–Smale theorem”, printed pp. 226–232 (Theorem 7.5, Corollary 7.6) (standard reference, not scraped)