{ "cells" : [ { "cell_origin" : "client", "cell_type" : "latex", "cells" : [ { "cell_origin" : "client", "cell_type" : "latex_view", "source" : "\\algorithm{expand_delta}{Expand generalised Kronecker delta symbols}\n\nIn Cadabra the \\prop{KroneckerDelta} property indicates a generalised Kronecker\ndelta symbol. In order to expand it into standard two-index Kronecker deltas, use\n\\algo{expand_delta}, as in the example below." } ], "hidden" : true, "source" : "\\algorithm{expand_delta}{Expand generalised Kronecker delta symbols}\n\nIn Cadabra the \\prop{KroneckerDelta} property indicates a generalised Kronecker\ndelta symbol. In order to expand it into standard two-index Kronecker deltas, use\n\\algo{expand_delta}, as in the example below." }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\text{Attached property KroneckerDelta to~}\\delta\\left(\\#\\right).\\end{dmath*}" } ], "source" : "\\delta{#}::KroneckerDelta;" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\delta^{a}\\,_{b}\\,^{c}\\,_{d}\\end{dmath*}" } ], "source" : "ex:=\\delta^{a}_{b}^{c}_{d};" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\frac{1}{2}\\delta^{a}\\,_{b} \\delta^{c}\\,_{d} - \\frac{1}{2}\\delta^{c}\\,_{b} \\delta^{a}\\,_{d}\\end{dmath*}" } ], "source" : "expand_delta(_);" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\delta^{a}\\,_{m}\\,^{l}\\,_{n} \\delta_{a}\\,^{c}\\,_{b}\\,^{d}\\end{dmath*}" } ], "source" : "ex:=\\delta^{a}_{m}^{l}_{n} \\delta_{a}^{c}_{b}^{d};" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\left(\\frac{1}{2}\\delta^{a}\\,_{m} \\delta^{l}\\,_{n} - \\frac{1}{2}\\delta^{l}\\,_{m} \\delta^{a}\\,_{n}\\right) \\left(\\frac{1}{2}\\delta_{a}\\,^{c} \\delta_{b}\\,^{d} - \\frac{1}{2}\\delta_{b}\\,^{c} \\delta_{a}\\,^{d}\\right)\\end{dmath*}" }, { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\frac{1}{4}\\delta^{a}\\,_{m} \\delta^{l}\\,_{n} \\delta_{a}\\,^{c} \\delta_{b}\\,^{d} - \\frac{1}{4}\\delta^{a}\\,_{m} \\delta^{l}\\,_{n} \\delta_{b}\\,^{c} \\delta_{a}\\,^{d} - \\frac{1}{4}\\delta^{l}\\,_{m} \\delta^{a}\\,_{n} \\delta_{a}\\,^{c} \\delta_{b}\\,^{d}+\\frac{1}{4}\\delta^{l}\\,_{m} \\delta^{a}\\,_{n} \\delta_{b}\\,^{c} \\delta_{a}\\,^{d}\\end{dmath*}" }, { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\frac{1}{4}\\delta^{l}\\,_{n} \\delta_{m}\\,^{c} \\delta_{b}\\,^{d} - \\frac{1}{4}\\delta^{l}\\,_{n} \\delta_{b}\\,^{c} \\delta_{m}\\,^{d} - \\frac{1}{4}\\delta^{l}\\,_{m} \\delta_{n}\\,^{c} \\delta_{b}\\,^{d}+\\frac{1}{4}\\delta^{l}\\,_{m} \\delta_{b}\\,^{c} \\delta_{n}\\,^{d}\\end{dmath*}" }, { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\frac{1}{4}\\delta_{b}\\,^{d} \\delta^{c}\\,_{m} \\delta^{l}\\,_{n} - \\frac{1}{4}\\delta_{b}\\,^{c} \\delta^{d}\\,_{m} \\delta^{l}\\,_{n} - \\frac{1}{4}\\delta_{b}\\,^{d} \\delta^{c}\\,_{n} \\delta^{l}\\,_{m}+\\frac{1}{4}\\delta_{b}\\,^{c} \\delta^{d}\\,_{n} \\delta^{l}\\,_{m}\\end{dmath*}" } ], "source" : "expand_delta(_);\ndistribute(_);\neliminate_kronecker(_);\ncanonicalise(_);" }, { "cell_origin" : "client", "cell_type" : "latex", "cells" : [ { "cell_origin" : "client", "cell_type" : "latex_view", "source" : "Note that it is in principle possible to get a result similar to the expanded form by using the \nYoung projector and then canonicalising, but this is more expensive:" } ], "hidden" : true, "source" : "Note that it is in principle possible to get a result similar to the expanded form by using the \nYoung projector and then canonicalising, but this is more expensive:" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\delta^{a}\\,_{b}\\,^{c}\\,_{d}\\end{dmath*}" } ], "source" : "ex:=\\delta^{a}_{b}^{c}_{d};" }, { "cell_origin" : "client", "cell_type" : "input", "cells" : [ { "cell_origin" : "server", "cell_type" : "latex_view", "source" : "\\begin{dmath*}{}\\delta^{a}\\,_{b}\\,^{c}\\,_{d}\\end{dmath*}" } ], "source" : "young_project_tensor(_);" }, { "cell_origin" : "client", "cell_type" : "input", "source" : "" } ], "description" : "Cadabra JSON notebook format", "version" : 1 }