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CounterexampleConstruction: AI-adaptedVerification: AI-adaptedPipeline-generatedjudge pass (gpt-5.6-terra)
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.

A surjective map need not be a fibration

Statement refuted

Every continuous surjection is a Serre fibration (and hence, more strongly, every continuous surjection is a Hurewicz fibration).

Facts & Assumptions

[F1]

A Serre or Hurewicz fibration lifts every path with prescribed initial point, since its test class contains D0. Hurewicz and serre fibrations

[F2]

Continuity means preimages of open sets are open. Continuity of a map of topological spaces at a point and globally

[F3]

The map [t](cos2πt,sin2πt) is a homeomorphism from R/Z onto the geometric circle. [t](cos2πt,sin2πt) is a homeomorphism from R/Z to the unit circle

[F4]

The subtraction formulas express the sine and cosine of a difference. The subtraction formulas for sine and cosine

[F5]

The sine zero set is πZ, and sine and cosine are 2π-periodic. The zero sets of sine and cosine and the least positive common period 2 pi

[F9]

The Pythagorean identity gives cos2u+sin2u=1 for every real u. Parity and the Pythagorean identity for sine and cosine

[F10]

The shift identity is cos(u+π)=cosu, with cos0=1. Quarter-turn values and shifts by pi/2 and pi

Counterexample

Given: q:[0,1]S1, q(t)=e2πit, and the path β(s)=eπis beginning at 1=q(0).

1.1

Let Q:RS1 be Q(t)=e2πit, so q=Q[0,1]. We first verify locally the equality-of-values clause in F3 on the full real-line map Q. If Q(x)=Q(y), F4 and F9 give sin(2π(xy))=0 and cos(2π(xy))=1. By F5, 2π(xy)=mπ. F10 gives cos((m+1)π)=cos(mπ) and cos0=1, so integer induction in both directions gives cos(mπ)=(1)m. Since the difference cosine is one, m is even and xyZ. Conversely F5's 2π-periodicity gives Q(x)=Q(y) whenever xyZ. Thus this clause no longer depends on the affected published inference. F3 makes Q continuous and onto; every real coset has a representative in [0,1], so q is continuous and onto. It is also a quotient map: a closed subset K of [0,1] is compact by F6 and F7. Its image is compact since pulling an open cover back by q gives an open cover of K, whose finite subcover maps to a finite cover of q(K). The geometric circle is Hausdorff (disjoint sufficiently small Euclidean balls separate distinct points), so F8 makes q(K) closed. Thus q is closed. If q1(A) is closed, surjectivity gives A=q(q1(A)) closed; with continuity this is the quotient criterion. For the refuted statement only continuity and surjectivity are needed. The path β(s)=(cos(πs),sin(πs))=Q(s/2) is continuous.

F2F3F4F5F6F7F8F9F10
2.1

Suppose a lift :I[0,1] has (0)=0. For 0<s1, the equation Q((s))=Q(s/2)=β(s) means (s)+s/2 is an integer by the locally verified clause in step 1.1. Because 0(s)1 and 0<s/21/2, that integer must be 1, so (s)=1s/2. In particular (s)1/2 for every s>0.

step 1.1assume-hyp
3.1

The set [0,1/4) is a relatively open neighbourhood of (0)=0. By step 2.1 its inverse image is exactly {0}, which is not open in I since every relative neighbourhood of zero contains positive numbers. This contradicts F2, so no such lift is continuous. F1 therefore excludes both Serre and Hurewicz fibrations. The failure occurs at the initial endpoint, despite the unique possible positive-time lift and the value (1)=1/2. All spaces are nonempty and all paths were explicit; no AC is involved.

F1F2step 2.1

Depends on

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