An algebraic loop (or reduced quasigroup) describes the closed binary multiplication of a set of "unsigned elements" (the product of
appears in the
position). The companion Demonstration, Algebraic Loops (2), shows how an algebraic loop also acts as a Cayley multiplication table for unsigned vectors (ordered sets of elements such as
The tables have indices
in the first row and first column (making them "reduced"), and each index occurs once in each row and column (making them "quasigroups"). Many loops exist, in many isomorphic forms; a selection (with
up to 16) demonstrates various features.
Algebraic loops with the associative property are groups, but other properties (Abelian, alternative, ..., Moufang, ..., etc.) are also important. 48 loops and 14 properties are offered here, together with three "folding" operations that convert symmetrical loops to algebras with "generalized signs". Signs
are taken to be fundamental concepts in most mathematical texts and are assumed to be unique square roots and fourth roots of +1. They arise from the folding of symmetrical multiplication tables. Their uniqueness is disproved by Clifford algebras
, which involve
entities that are square roots and
entities that are fourth roots of +1, together with a "pseudoscalar"
that is an anticommutative version of
. Ternary symmetry leads to signs 𝕛 and 𝕁 that are cube roots of +1:
. Fifth and higher prime roots are generators of groups, but are probably of little physical significance. The generalization of signs by the folding of loops appears to be a new concept.
Choose a loop and a test. The table, and the condition that is tested (for all
, … in the symbolic table) will appear, together with the result. Alternative loops (which include octonions) have "square-associativity" and subsume both associative loops (groups) and Moufang loops. The Moufang property ensures that any vector has a multiplicative inverse. Many more properties exist than are demonstrated here but most are of only specialized interest.
You can also test whether a table has
-fold symmetry (for
). If it does (usually indicated in the descriptive header), the top-left corner of the table can be converted into an "
-signed algebra" for "
give algebras over real and complex fields with signs
gives a complete "terplex" algebra with signs
(primitive cube roots of +1, NOT cyclotomic complex numbers). If the loop can be folded, partitions will appear and indices greater than
will be replaced by signed indices. Note that different isomorphisms of the same loop may not fold or may fold to different algebras.
Other Demonstrations develop algebras and generalized signs in more detail. I use the neologism "hoops" for "symmetry conserving vector-division algebras" (all groups, a few non-associative Moufang loops, and many signed-table algebras); the factors of their symbolic determinants are conserved symmetries that may (by Noether's theorem) relate to forces and particles. Symmetry conservation is central to modern physics, so non-conservative algebras are unlikely to be relevant to physics.