On the Reconstruction of SAS from Other Triangle Congruence Criteria, Part II: Eliminating the Pons Asinorum
Abstract
In the first part of this work we showed that, within a Hilbert plane deprived of the Side-Angle-Side axiom, the Side-Angle-Angle criterion, together with a ray correspondence principle [\textbf{RCT}], the existence of angle bisectors [\textbf{AB}], the congruence of supplements of congruent angles [\textbf{SA}], and the Pons Asinorum [\textbf{PA}], suffices to reconstruct SAS. We left open the question of whether [\textbf{PA}] is genuinely required alongside the other three principles, noting only a qualitative asymmetry in the nature of the principles involved. In this second part we answer this question: we show that SAA, [RCT], [AB] ⊢ [PA], so that [\textbf{PA}] is redundant among the hypotheses of our main theorem, which improves to SAA, [RCT], [AB], [SA] ⊢ SAS. The proof adapts an argument recently given by Donnelly, who reconstructs SAS from SAA together with an angle addition axiom and the existence of angle bisectors.
Related
- On the Reconstruction of SAS from Other Triangle Congruence Criteria
- Congruence spectra and geometric reconstruction of T-algebras
- Reflected BSDEs under random horizons: Sharp support criteria, irregular reflection, and Cox reconstruction
- An Improved Minimization Method: Eliminating Shift and Variance Inflation While Maintaining Marginal Balance
- Eliminating the Higgs field and perturbing Yang-Mills connections in cone Yang-Mills theory
BibTeX
@misc{volpe2026reconstruction,
title = {{On the Reconstruction of SAS from Other Triangle Congruence Criteria, Part II: Eliminating the Pons Asinorum}},
author = {Roberto Volpe},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21385},
eprint = {2609.21385},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21385},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - On the Reconstruction of SAS from Other Triangle Congruence Criteria, Part II: Eliminating the Pons Asinorum
AU - Roberto Volpe
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21385
UR - https://arxiv.org/abs/2609.21385
AB - In the first part of this work we showed that, within a Hilbert plane deprived of the Side-Angle-Side axiom, the Side-Angle-Angle criterion, together with a ray correspondence principle [\textbf{RCT}], the existence of angle bisectors [\textbf{AB}], the congruence of supplements of congruent angles [\textbf{SA}], and the Pons Asinorum [\textbf{PA}], suffices to reconstruct SAS. We left open the question of whether [\textbf{PA}] is genuinely required alongside the other three principles, noting only a qualitative asymmetry in the nature of the principles involved. In this second part we answer this question: we show that SAA, [RCT], [AB] ⊢ [PA], so that [\textbf{PA}] is redundant among the hypotheses of our main theorem, which improves to SAA, [RCT], [AB], [SA] ⊢ SAS. The proof adapts an argument recently given by Donnelly, who reconstructs SAS from SAA together with an angle addition axiom and the existence of angle bisectors.
ER -