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In this short note, we construct solutions to quantum tetrahedron equation of the kind "with variables on the edges". Each of these variables takes just two values, called sometimes "colors". We propose two different constructions. The first of them involves, in particular, two $\mathcal R$-operators each depending on one parameter, while these parameters are independent from each other; the number of nonvanishing matrix entries in these two $\mathcal R$-operators is either 12 or 14. In the second construction, we use what may be called "modified tetrahedron in a direct sum" to produce, again, quantum tetrahedron solutions. All matrix entries of our $\mathcal R$-operators are nonnegative, if the relevant parameters are chosen properly., Comment: 9 pages; v2: one more construction added

A new version of the self-similarity spin transform on three-dimensional cubic lattices is proposed that makes possible calculation of nontrivial spin correlations in a "combinatorial" model, in which all permitted spin configurations have equal probabilities., Comment: 27 pages, 4 tikz figures

A family of heptagon relations -- algebraic imitations of five-dimensional Pachner moves -- is constructed, parameterized by simplicial 3-cocycles. These relations are shown to possess a nontrivial "heptagon cohomology", which yields invariants of a pair "manifold, its 3rd cohomology class"., Comment: 23 pages

Cubic blocks are studied assembled from linear operators $\mathcal R$ acting in the tensor product of $d$ linear "spin" spaces. Such operator is associated with a linear transformation $A$ in a vector space over a field $F$ of a finite characteristic $p$, like "permutation-type" operators studied by Hietarinta. One small difference is that we do not require $A$ and, consequently, $\mathcal R$ to be invertible; more importantly, no relations on $\mathcal R$ are required of the type of Yang--Baxter or its higher analogues. It is shown that, in $d=3$ dimensions, a $p^n\times p^n\times p^n$ block decomposes into the tensor product of operators similar to the initial $\mathcal R$. One generalization of this involves commutative algebras over $F$ and allows to obtain, in particular, results about spin configurations determined by a four-dimensional $\mathcal R$. Another generalization deals with introducing Boltzmann weights for spin configurations; it turns out that there exists a non-trivial self-similarity involving Boltzmann weights as well., Comment: 33 pages, 10 figures. v3: conjecture about self-similarity in any finite characteristic is now proven

A cohomology theory for "odd polygon" relations -- algebraic imitations of Pachner moves in dimensions 3, 5, ... -- is constructed. Manifold invariants based on polygon relations and nontrivial polygon cocycles are proposed. Example calculation results are presented., Comment: 32 pages. v2: proof of Proposition 13 made more accurate; new calculation results added to Table 2. This article supersedes arXiv:2110.08780