Английская Википедия:Homotopy group with coefficients
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In topology, a branch of mathematics, for <math>i \ge 2</math>, the i-th homotopy group with coefficients in an abelian group G of a based space X is the pointed set of homotopy classes of based maps from the Moore space of type <math>(G, i)</math> to X, and is denoted by <math>\pi_i(X; G)</math>.[1] For <math>i \ge 3</math>, <math>\pi_i(X; G)</math> is a group. The groups <math>\pi_i(X; \Z)</math> are the usual homotopy groups of X.
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