From 0d7746bc8dbe22bd5ce4ece76354e34454eda5d2 Mon Sep 17 00:00:00 2001 From: Michael Orlitzky Date: Wed, 3 Mar 2021 21:22:02 -0500 Subject: [PATCH] eja: add some more octonion tests. --- mjo/eja/eja_algebra.py | 55 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 52 insertions(+), 3 deletions(-) diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py index 3659694..afe0a67 100644 --- a/mjo/eja/eja_algebra.py +++ b/mjo/eja/eja_algebra.py @@ -2587,10 +2587,10 @@ class QuaternionHermitianEJA(ConcreteEJA, QuaternionMatrixEJA): class OctonionHermitianEJA(FiniteDimensionalEJA, MatrixEJA): r""" - SETUP:: - sage: from mjo.eja.eja_algebra import OctonionHermitianEJA + sage: from mjo.eja.eja_algebra import (FiniteDimensionalEJA, + ....: OctonionHermitianEJA) EXAMPLES: @@ -2602,7 +2602,47 @@ class OctonionHermitianEJA(FiniteDimensionalEJA, MatrixEJA): ....: check_axioms=True) # long time Euclidean Jordan algebra of dimension 27 over Rational Field - TESTS:: + After a change-of-basis, the 2-by-2 algebra has the same + multiplication table as the ten-dimensional Jordan spin algebra:: + + sage: b = OctonionHermitianEJA._denormalized_basis(2,QQ) + sage: basis = (b[0] + b[9],) + b[1:9] + (b[0] - b[9],) + sage: jp = OctonionHermitianEJA.jordan_product + sage: ip = OctonionHermitianEJA.trace_inner_product + sage: J = FiniteDimensionalEJA(basis, + ....: jp, + ....: ip, + ....: field=QQ, + ....: orthonormalize=False) + sage: J.multiplication_table() + +----++----+----+----+----+----+----+----+----+----+----+ + | * || b0 | b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8 | b9 | + +====++====+====+====+====+====+====+====+====+====+====+ + | b0 || b0 | b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8 | b9 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b1 || b1 | b0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b2 || b2 | 0 | b0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b3 || b3 | 0 | 0 | b0 | 0 | 0 | 0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b4 || b4 | 0 | 0 | 0 | b0 | 0 | 0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b5 || b5 | 0 | 0 | 0 | 0 | b0 | 0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b6 || b6 | 0 | 0 | 0 | 0 | 0 | b0 | 0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b7 || b7 | 0 | 0 | 0 | 0 | 0 | 0 | b0 | 0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b8 || b8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | b0 | 0 | + +----++----+----+----+----+----+----+----+----+----+----+ + | b9 || b9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | b0 | + +----++----+----+----+----+----+----+----+----+----+----+ + + TESTS: + + We can actually construct the 27-dimensional Albert algebra, + and we get the right unit element if we recompute it:: sage: J = OctonionHermitianEJA(3, # long time ....: field=QQ, # long time @@ -2619,6 +2659,15 @@ class OctonionHermitianEJA(FiniteDimensionalEJA, MatrixEJA): | 0 | 0 | e0 | +----+----+----+ + The 2-by-2 algebra is isomorphic to the ten-dimensional Jordan + spin algebra, but just to be sure, we recompute its rank:: + + sage: J = OctonionHermitianEJA(2, # long time + ....: field=QQ, # long time + ....: orthonormalize=False) # long time + sage: J.rank.clear_cache() # long time + sage: J.rank() # long time + 2 """ def __init__(self, n, field=AA, **kwargs): if n > 3: -- 2.44.2