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Presets: Koebe · z/(1−z) · z·exp(z/2) · log(1+z) · arctan(z) · sin(z) · z+z² (not starlike)
Ma-Minda extremals: cardioid · lemniscate · ℘ cardioid · 3-leaf · 4-leaf · epi-3 · epi-6

Counterexamples found with this tool

Every row is a certified disproof a run like the one above produced: a point z on |z| = r where interval arithmetic guarantees Re(zf′/f) < 0, so f cannot be starlike there. A sound witness, not a sampled point.

These are computational non-membership facts, not refutations of any published theorem - most are special functions that are starlike only on a smaller sub-disk, or synthetic test cases. We record them as honest negative results.

Filtered to q-exponential e_q(z). Show all →
7Counterexample facts
FamilyClosed form / ParamsProperty Representative witness zRe(zf′/f) ≤ Proven rWitnesses
q-exponential e_q(z)
{'q': 0.15}
starlike 0.99*exp(i*2.988195) Re ≤ -0.3983 r ≤ 0.950
2 runs
  1. #674 · 0.99*exp(i*2.988195) · Re ≤ -0.3983 · r ≤ 0.950 · boundary_scan_centered_v31
  2. #1026 · 0.9900*exp(i*3.00197) · Re ≤ -0.3870 · r ≤ 0.950 · pointwise_starlike_iv
q-exponential e_q(z)
{'q': 0.175}
starlike 0.99*exp(i*2.992797) Re ≤ -0.0586 r ≤ 0.950
2 runs
  1. #675 · 0.99*exp(i*2.992797) · Re ≤ -0.0586 · r ≤ 0.950 · boundary_scan_centered_v31
  2. #1027 · 0.9900*exp(i*3.00197) · Re ≤ -0.0504 · r ≤ 0.950 · pointwise_starlike_iv
q-exponential e_q(z)
{'q': 0.1}
starlike 0.95*exp(i*2.988195) Re ≤ -0.5560 r ≤ 0.900
2 runs
  1. #660 · 0.95*exp(i*2.988195) · Re ≤ -0.5560 · r ≤ 0.900 · boundary_scan_centered_v31
  2. #993 · 0.9900*exp(i*3.00197) · Re ≤ -2.0836 · r ≤ 0.900 · pointwise_starlike_iv
q-exponential e_q(z)
{'q': 0.125}
starlike 0.95*exp(i*3.291923) Re ≤ -0.1437 r ≤ 0.900
2 runs
  1. #673 · 0.95*exp(i*3.291923) · Re ≤ -0.1437 · r ≤ 0.900 · boundary_scan_centered_v31
  2. #1025 · 0.9900*exp(i*3.00197) · Re ≤ -0.9907 · r ≤ 0.900 · pointwise_starlike_iv
q-exponential e_q(z)
{'q': 0.075}
starlike 0.9*exp(i*2.992797) Re ≤ -0.0508 r ≤ 0.800
2 runs
  1. #672 · 0.9*exp(i*2.992797) · Re ≤ -0.0508 · r ≤ 0.800 · boundary_scan_centered_v31
  2. #1024 · 0.9900*exp(i*2.68781) · Re ≤ -4.1780 · r ≤ 0.800 · pointwise_starlike_iv
q-exponential e_q(z)
{'q': 0.05}
starlike 0.9900*exp(i*2.68781) Re ≤ -8.5270 r ≤ - 1
q-exponential e_q(z)
{'q': 0.025}
starlike 0.9900*exp(i*-2.09440) Re ≤ -20.0265 r ≤ - 1
How to read a witness
z = r·exp(i·θ) is a point on the boundary circle of radius r in the unit disk. The verifier bounds Re(zf′(z)/f(z)) over a small arc around z with mpmath interval arithmetic; the upper bound shown is strictly negative, so Re(zf′/f) < 0 on the whole arc - f cannot be starlike on a disk containing z. Proven, not approximated.  Programmatic access: GET /api/v2/counterexamples
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