3. Show HN: ZeroCloudPDF Sign (zerocloudpdf.com)

Add your signature to a PDF free online. Draw, upload, or type it, then place it anywhere on any page. No uploads, no signup, 100% private.

22. Italy putting nearly all major cities on highest heat alert (www.bbc.com)

Some 19 major Italian cities - including Rome, Milan and Naples - are already on red alert, and by Monday all but two will be.

Nineteen major cities in Italy, including Rome and Milan, are facing extreme heat alerts, with nearly all expected to be affected by Monday. This situation highlights the growing concern over climate conditions in urban areas.

24. Show HN: Arabic–Hebrew artifact in GPT-5.4, 12,160 frozen trials (zenodo.org)

This preprint reports a locally frozen 12,160-trial black-box evaluation of prompt-conditioned Arabic–Hebrew hybrid artifact formation in the dated gpt-5.4-2026-03-05 Chat Completions endpoint. The study comprises 10,240 primary trials across two exact system conditions and every integer output-token ceiling from 1 through 1,024, plus 1,920 frozen control and ablation trials. Classification used exact, untrimmed, unnormalized provider-returned UTF-8 bytes and logical code-point order. The primary census observed 7,253 exact assigned artifacts (70.8301%) and 7,293 mixed-script outputs (71.2207%). The dotted condition produced 4,830/5,120 exact T1 artifacts (94.3359%), while the undotted condition produced 2,423/5,120 exact T0 artifacts (47.3242%). Every exact artifact matched the dotted-versus-undotted identity assigned by its system condition, yielding 7,253/7,253 prompt-congruent exact outputs. The prospectively fixed pooled exact-rate threshold was not met because its Wilson lower bound was 69.9420%, while the prompt-congruence threshold was met with a Wilson lower bound of 99.9471%. The study further documents a 47.0117-percentage-point dotted–undotted rate difference, complete control and ablation results, token-ceiling trajectories, discovery-versus-replication divergence, Unicode morphology, and full operational-error accounting. A separately implemented verifier reconstructed all 12,160 retained attempt records and replayed 24,323 hash-chained events with zero classifier disagreements, no chain breaks, and no missing terminal slots. The findings establish a reproducible, code-point-specific black-box behavioral object and identify the dotted condition as the stable branch in the tested execution window, without claiming an internal mechanism, causality, intention, training-data provenance, or cross-vendor generality.

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