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Difference between revisions of "Kernel of a loop"

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The set of elements of the [[Loop|loop]] that are simultaneously left-, right- and middle-associative (or, equivalently, the intersection of the left, right and middle kernels of the loop). An element <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/k/k055/k055270/k0552701.png" /> of a loop is called left-associative if <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/k/k055/k055270/k0552702.png" /> for any <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/k/k055/k055270/k0552703.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/k/k055/k055270/k0552704.png" /> in the loop. The set of left-associative elements is called the left kernel of the loop. Right- and middle-associative elements and the corresponding kernels are defined similarly. Left and right kernels can also be defined for quasi-groups, but only loops have a non-empty middle kernel. All the kernels of a loop are subgroups of it. All three kernels of a <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/k/k055/k055270/k0552705.png" />-loop coincide, and for Moufang loops (cf. [[Moufang loop|Moufang loop]]) they form, in addition, a normal subloop (see [[Loop|Loop]]).
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The set of elements of the [[loop]] that are simultaneously left-, right- and middle-associative (or, equivalently, the intersection of the left, right and middle kernels of the loop). An element $a$ of a loop is called left-associative if $a(bc) = (ab)c$ for any $b,c$ in the loop. The set of left-associative elements is called the left kernel of the loop. Right- and middle-associative elements and the corresponding kernels are defined similarly. Left and right kernels can also be defined for quasi-groups, but only loops have a non-empty middle kernel. All the kernels of a loop are subgroups of it. All three kernels of a loop with the invertibility property ($IP$-loop) coincide, and for [[Moufang loop]]s they form, in addition, a normal subloop (see [[Loop]]).
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Revision as of 20:02, 29 October 2016

The set of elements of the loop that are simultaneously left-, right- and middle-associative (or, equivalently, the intersection of the left, right and middle kernels of the loop). An element $a$ of a loop is called left-associative if $a(bc) = (ab)c$ for any $b,c$ in the loop. The set of left-associative elements is called the left kernel of the loop. Right- and middle-associative elements and the corresponding kernels are defined similarly. Left and right kernels can also be defined for quasi-groups, but only loops have a non-empty middle kernel. All the kernels of a loop are subgroups of it. All three kernels of a loop with the invertibility property ($IP$-loop) coincide, and for Moufang loops they form, in addition, a normal subloop (see Loop).

How to Cite This Entry:
Kernel of a loop. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Kernel_of_a_loop&oldid=12905
This article was adapted from an original article by O.A. Ivanova (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article