Geometric Proof Research Articles

Mirrors to Del Pezzo Surfaces and the Classification of $T$-Polygons

We give a new geometric proof of the classification of $T$-polygons, a theorem originally due to Kasprzyk, Nill and Prince, using ideas from mirror symmetry. In particular, this gives a completely geometric proof that any two toric $\mathbb{Q}$-Gorenstein degenerations of a smooth del Pezzo $X$ surface are connected via trees of rational curves in the moduli space of $X$.

A Natural Geometric Proof of the Length-Curvature Identity

Summary This note offers a natural geometric proof for the length-curvature identity for a C 2 function of two variables.

Tropical Refined Curve Counting with Descendants

We prove a q-refined tropical correspondence theorem for higher genus descendant logarithmic Gromov–Witten invariants with a λg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _g$$\\end{document} class in toric surfaces. Specifically, a generating series of such logarithmic Gromov–Witten invariants agrees with a q-refined count of rational tropical curves satisfying higher valency conditions. As a corollary, we obtain a geometric proof of the deformation invariance of this tropical count. In particular, our results give an algebro-geometric meaning to the tropical count defined by Blechman and Shustin. Our strategy is to use the logarithmic degeneration formula, and the key new technique is to reduce to computing integrals against double ramification cycles and connect these integrals to the non-commutative KdV hierarchy.

Geometric diagrams as an effective notation

AbstractIn what way does a mathematical proof depend on the notation used in its presentation? This paper examines this question by analysing the computational differences, in the sense of Larkin and Simon's ‘Why a diagram is (sometimes) worth 10,000 words’, between diagrammatic and sentential notations as a means for presenting geometric proofs. Wittgenstein takes up the question of mathematical notation and proof in Section III of Remarks on the Foundations of Mathematics. After discussing his observations on a proof's ‘characteristic visual shape’ in Section III with respect to arithmetical proofs, the paper shows how the notion of a characteristic visual shape illuminates the special effectiveness of diagrammatic notation in geometry.

On the positivity of B-spline Wronskians

A proof that Wronskians of non-zero B-splines are positive is given, using only recursive formulas for B-splines and their derivatives. This could be used to generalize the de Boor–DeVore geometric proof of the Schoenberg–Whitney conditions and total positivity of B-splines to Hermite interpolation. For Wronskians of maximal order with respect to a given degree, positivity follows from a simple formula.

A Geometric Proof of the Polygonal Isoperimetric Inequality

A Geometric Proof of the Polygonal Isoperimetric Inequality

The Integration of Digital Technology in Task-Design on Eye-Tracking Studies in Geometry

Eye-tracking (ET) method provides a promising channel for educational researchers to connect learning outcomes to cognitive processes. The main principle of ET is that our gaze and our focus of attention are connected. Due to the advent of digital technologies, eye tracking studies are increasingly growing in different fields and in mathematics education. We assume that the provided task is one of the ways to analyse deeply cognitive processes, and we wonder how ET studies are dealing with the integration of digital technology in task-design in geometry. Starting from Strohmaier et al. (2020) we found three studies, one focused on geometric proofs and two based on construction of geometric objects. We highlight the contributions of integrating digital technology in learning and instruction, and in research in geometry.

A Unified Geometric Proof of Aristarchus’ Inequality

Summary We present a refined, simplified, and unified proof of Aristarchus’ inequality, without resorting to trigonometry, calculus or extended geometric arguments.

Symplectic Fourier–Deligne Transforms on G/U and the Algebra of Braids and Ties

Abstract We explicitly identify the algebra generated by symplectic Fourier–Deligne transforms (i.e., convolution with Kazhdan–Laumon sheaves) acting on the Grothendieck group of perverse sheaves on the basic affine space $G/U$, answering a question originally raised by A. Polishchuk. We show it is isomorphic to a distinguished subalgebra, studied by I. Marin, of the generalized algebra of braids and ties (defined in Type $A$ by F. Aicardi and J. Juyumaya and generalized to all types by Marin), providing a connection between geometric representation theory and an algebra defined in the context of knot theory. Our geometric interpretation of this algebra entails some algebraic consequences: we obtain a short and type-independent geometric proof of the braid relations for Juyumaya’s generators of the Yokonuma–Hecke algebra (previously proved case-by-case in types $A, D, E$ by Juyumaya and separately for types $B, C, F_{4}, G_{2}$ by Juyumaya and S. S. Kannan), a natural candidate for an analogue of a Kazhdan–Lusztig basis, and finally an explicit formula for the dimension of Marin’s algebra in Type $A_{n}$ (previously only known for $n \leq 4$).

A geometric proof for the root-independence of the greedoid polynomial of Eulerian branching greedoids

We define the root polytope of a regular oriented matroid, and show that the greedoid polynomial of an Eulerian branching greedoid rooted at vertex v0 is equivalent to the h⁎-polynomial of the root polytope of the dual of the graphic matroid.As the definition of the root polytope is independent of the vertex v0, this gives a geometric proof for the root-independence of the greedoid polynomial for Eulerian branching greedoids, a fact which was first proved by Swee Hong Chan, Kévin Perrot and Trung Van Pham using sandpile models. We also obtain that the greedoid polynomial does not change if we reverse every edge of an Eulerian digraph.

Constant term functors with $\mathbb{F}_{p}$-coefficients

We study the constant term functor for \mathbb{F}_{p} -sheaves on the affine Grassmannian in characteristic p with respect to a Levi subgroup. Our main result is that the constant term functor induces a tensor functor between categories of equivariant perverse \mathbb{F}_{p} -sheaves. We apply this fact to get information about the Tannakian monoids of the corresponding categories of perverse sheaves. As a byproduct we also obtain geometric proofs of several results due to Herzig on the mod p Satake transform and the structure of the space of mod p Satake parameters.

How Schwarzschild could have discovered and fixed the problem with his metric

Karl Schwarzschild's landmark paper revealed the first ever exact solution to Einstein's gravitational field equation. This was a major scientific achievement. However, his solution for the metric of a spherically symmetric spacetime is different than the one found in textbooks today—because Schwarzschild assumed, like in Newtonian gravity, that only one singularity could exist. Given the newness of Einstein's general theory of relativity and the existing paradigm of Newtonian gravity, his assumption was natural. While other authors have previously pointed out this shortcoming and corrected it, the contribution of this paper is to show how Schwarzschild might have discovered it himself. A simple geometric proof indicates how Schwarzschild, with a different assignment of a single constant of integration, would have arrived at the metric found in textbooks today.

Exploring decision-making prospective mathematics teacher in solving geometric proof problems

Facing the current digital era, correct and accurate decisions are needed to deal with the problems. This research aimed to explore the decision-making abilities of prospective mathematics teacher students in solving geometric proof problems. This research was a qualitative descriptive study with research subjects 3 out of 32 students of the 2nd semester Mathematics Education study program. The research instrument is the researcher himself, who is assisted with geometric proof problem tests and interview guidelines. Data analysis was including reduction, presentation, and conclusion. The validity of the research data was tested using methods triangulation. The research results show that subjects with a proof ability of K2 can build and clarify geometric concepts/principles and can assess the reasonableness of ideas even though the subject feels unsure about their choice. Subjects with a proof ability of K3 can build and clarify geometric concept/principle ideas but cannot assess the reasonableness of proof ideas. Subjects with a proof ability of K4 can build ideas of geometric concepts/principles, can clarify even though they are incomplete, and cannot assess the reasonableness of proof ideas. Students need to be equipped with decision-making skills in solving proof problems as preparation to become mathematics teachers in the future.

A Rigorous Euclidean Geometric Proof of the Cube Duplication Impossibility

A Rigorous Euclidean Geometric Proof of the Cube Duplication Impossibility

An update on Haiman’s conjectures

Abstract We revisit Haiman’s conjecture on the relations between characters of Kazdhan–Lusztig basis elements of the Hecke algebra over $S_n$ . The conjecture asserts that, for purposes of character evaluation, any Kazhdan–Lusztig basis element is reducible to a sum of the simplest possible ones (those associated to so-called codominant permutations). When the basis element is associated to a smooth permutation, we are able to give a geometric proof of this conjecture. On the other hand, if the permutation is singular, we provide a counterexample.

Wittgenstein on Proof and Concept-Formation

Abstract In his Remarks on the Foundations of Mathematics, Wittgenstein claims, puzzlingly, that ‘the proof creates a new concept’ (RFM III-41). This paper aims to contribute to clarifying this idea, and to showing how it marks a major break with the traditional conception of proof. Moreover, since the most natural way to understand his claim is open to criticism, a secondary goal of what follows is to offer an interpretation of it that neutralizes the objection. The discussion proceeds by analysing a well-known geometrical proof.

A Comparative Study of Secondary School Mathematics Teaching Materials from the Perspective of Reasoning--Taking "Pythagorean Theorem" as an Example

Education has always been a hot topic of discussion. From the results of junior high school mathematics assessments in recent years, there are differences in mathematical abilities between Eastern Europe and Europe and America. Since reasoning is crucial to understanding mathematics, we compare the "Pythagorean Theorem" in textbooks from China, the United States, and Singapore, examining the theorem's different types of reasoning and how it relates to previously acquired knowledge. The reasoning categories proposed by Shi Ningzhong, Harel, and Sowder serve as the fundamental basis for categorizing the varieties of reasoning in this research. The introduction of proofs for the hook and Pythagorean theorem is investigated for each edition of the textbook, and concerning the deductive reasoning ability, the People's Education Press edition (PEP) and Zhejiang Education edition (ZJE) editions are in the first tier, followed by Singaporean textbooks and American textbooks. In terms of the correlation between the Pythagorean theorem and what has been learned, the ZJE involves the most points of correlation. Finally, we discuss the implications of these results for teachers' explanations of the Pythagorean theorem: teachers can briefly introduce the geometric deductive proof process of the Pythagorean theorem to stimulate students' interest in learning mathematics.

Secondary teachers’ geometrical figure apprehension: their ability to construct geometrical proof and to predict students’ difficulties

The present study investigates in-service secondary teachers’ geometrical figure apprehension in relation to their ability to construct geometrical proofs and to predict didactically their students’ difficulties and mistakes. The theoretical framework of analysis is based on Duval’s geometrical figure apprehension which was taught to the teachers as part of an in-service training course in didactics of mathematics, offered by one of the researchers. As part of the course final assessment, a written test consisting of various geometrical tasks was constructed and administered to the sample. Participants’ answers in both solving and interpreting difficulties related to the tasks were analyzed. The results of the study indicate that theories and concepts of didactics of geometry can shed light to various facets of teaching and learning of geometry. A teacher who presents a correct solution at a task does not necessarily identify or understand the possible difficulties faced by students. Discussion concentrates on teaching implications about geometry and geometrical proof.

Characteristics of student errors in solving geometric proof problems based on Newman's theory

This study aims to determine the characteristics of student errors in solving geometry proof based on Newman's Theory. The research method used is a qualitative research method with a phenomenographic approach. This research was conducted to prevent students from repeating mistakes in advanced geometry courses. The types of errors based on Newman's Theory used in this study are: (1) reading errors in the representation of mathematical symbols; (2) comprehension errors of the proof problem; (3) transformation errors of the proof problem; (4) process skills errors of the proof problem; and (5) encoding errors. The subjects of this study were 15 students, and the instruments used were interview guidelines and documentation. The results of this study are reading errors in the representation of mathematical symbols with an average of 15.81%, with error characteristics that students do not write geometry symbols according to the rules. Comprehension errors of the proof problem with an average of 4.78%. Transformation errors of the proof problem with an average of 26.84%. Process skill errors of proof problems with an average of 29.04%. Encoding errors with an average of 23.53%.

A geometric approach to second-order differentiability of convex functions

We show a new, elementary and geometric proof of the classical Alexandrov theorem about the second order differentiability of convex functions. We also show new proofs of recent results about Lusin approximation of convex functions and convex bodies by C 1 , 1 C^{1,1} convex functions and convex bodies.