k <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b"> <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">𝑘</ci> </annotation-xml> {\displaystyle{\displaystyle k}}
ℓ <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b"> <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">ℓ</ci> </annotation-xml> {\displaystyle{\displaystyle\ell}}
ρ <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b"> <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">𝜌</ci> </annotation-xml> {\displaystyle{\displaystyle\rho}}
η <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b"> <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">𝜂</ci> </annotation-xml> {\displaystyle{\displaystyle\eta}}
a k <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b"> <apply id="p1.1.m1.1.3.cmml" xref="p1.1.m1.1.3"> <csymbol cd="ambiguous" id="p1.1.m1.1.3.1.cmml" xref="p1.1.m1.1.3">subscript</csymbol> <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">𝑎</ci> <ci id="p1.1.m1.1.2.1.cmml" xref="p1.1.m1.1.2.1">𝑘</ci> </apply> </annotation-xml> {\displaystyle{\displaystyle a_{k}}}