Multiplicative Modular Nim (MuM)
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arXiv
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| Format: | Preprint |
| Veröffentlicht: |
2025
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| _version_ | 1866908447192121344 |
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| author | Tyagi, Satyam |
| author_facet | Tyagi, Satyam |
| contents | We introduce Multiplicative Modular Nim (MuM), a variant of Nim in which the traditional nim-sum is replaced by heap-size multiplication modulo m. We establish a complete theory for this game, beginning with a direct, Bouton-style analysis for prime moduli. Our central result is an analogue of the Sprague-Grundy theorem, where we define a game-theoretic value, the mumber, for each position via a multiplicative mex recursion. We prove that these mumbers are equivalent to the heap-product modulo m, and show that for disjunctive sums of games, they combine via modular multiplication in contrast to the XOR-sum of classical nimbers. For composite moduli, we show that MuM decomposes via the Chinese Remainder Theorem into independent subgames corresponding to its prime-power factors. We extend the game to finite fields F(pn), motivated by the pedagogical need to make the algebra of the AES S-box more accessible. We demonstrate that a sound game in this domain requires a Canonical Heap Model to resolve the many-to-one mapping from integer heaps to field elements. To our knowledge, this is the first systematic analysis of a multiplicative modular variant of Nim and its extension into a complete, non-additive combinatorial game algebra. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_08830 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Multiplicative Modular Nim (MuM) Tyagi, Satyam Discrete Mathematics Combinatorics 91A46, 11A07 G.2.1 We introduce Multiplicative Modular Nim (MuM), a variant of Nim in which the traditional nim-sum is replaced by heap-size multiplication modulo m. We establish a complete theory for this game, beginning with a direct, Bouton-style analysis for prime moduli. Our central result is an analogue of the Sprague-Grundy theorem, where we define a game-theoretic value, the mumber, for each position via a multiplicative mex recursion. We prove that these mumbers are equivalent to the heap-product modulo m, and show that for disjunctive sums of games, they combine via modular multiplication in contrast to the XOR-sum of classical nimbers. For composite moduli, we show that MuM decomposes via the Chinese Remainder Theorem into independent subgames corresponding to its prime-power factors. We extend the game to finite fields F(pn), motivated by the pedagogical need to make the algebra of the AES S-box more accessible. We demonstrate that a sound game in this domain requires a Canonical Heap Model to resolve the many-to-one mapping from integer heaps to field elements. To our knowledge, this is the first systematic analysis of a multiplicative modular variant of Nim and its extension into a complete, non-additive combinatorial game algebra. |
| title | Multiplicative Modular Nim (MuM) |
| topic | Discrete Mathematics Combinatorics 91A46, 11A07 G.2.1 |
| url | https://arxiv.org/abs/2507.08830 |