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Canonical Key
z+z**2+z**3/2
Closed Form
f(z) = z + z^2 + z^3/2

Image domain \(f(\mathbb{D})\)

The image of the unit disk under \(f\): concentric circles \(|z|=r\) and radial spokes mapped through \(f(z)=z+a_2z^2+\dots\); the bold curve is the boundary \(f(e^{i\theta})\). Rendered in your browser from the certified Taylor coefficients - nothing is computed server-side.

Taylor series
r* ≈ 0.600
Radius of starlikeness r* ≈ 0.6000
disproven f is starlike on |z| < r*; the colored disk shows the certified region.

Unit disk explorer - hover to evaluate

Hover over the disk

Related

Univalence Criteria

Schwarzian norm ||S(f)||
2.038
✗ exceeds Nehari bound 2
Pre-Schwarzian norm ||T(f)||
1.521
✗ exceeds Becker bound 1

Facts (8)

Property Kind Params Holds Value / r Status Confidence
B membership {} 1.5210 ✗ disproven rigorous_verified
K membership {} -36.6828 unscreened -
N membership {} 2.0385 ✗ disproven rigorous_verified
||T(f)|| bound {} 1.5210 ✓ proven rigorous_verified
r* radius {} - r ≤ 0.779 🔬 screened numerical_strong
||S(f)|| bound {} 2.0385 ✓ proven rigorous_verified
S* membership {} r ≤ 0.600 ✗ disproven proven
S membership {} - unscreened -

Verification Runs (6)

Verifier Property Direction Outcome Domain r Witness Engine
boundary_scan_closed_form_v31 starlike disproves pass 0.600 0.8*exp(i*2.374602) boundary_v3.1
pointwise_nehari_univalent_iv nehari_univalent disproves pass 0.816 [-0.660334627425535, -0.4797611895392261] gft-0.1.0-reaudit-20260610
pointwise_becker_univalent_iv becker_univalent disproves pass 0.816 [-0.660334627425535, -0.4797611895392261] gft-0.1.0-reaudit-20260610
pointwise_starlike_iv starlike disproves pass 0.990 [-0.7121464023352646, -0.6877117867544074] gft-0.1.0-reaudit-20260610
boundary_scan_centered_v31 starlike disproves pass 0.600 0.8*exp(i*2.374602) boundary_v3.1
boundary_scan_polynomial starlike disproves pass 0.600 0.8*exp(i*2.374602) boundary_v3.0

Instances (1)

{}
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