(chemistry, physics) of, or relating to isotopes

(mathematics) Of two presemifields S {\displaystyle \mathbb {S} } and S ′ {\displaystyle \mathbb {S} '} of characteristic p {\displaystyle p} , when there exists three linear maps g 1 {\displaystyle g_{1}} , g 2 {\displaystyle g_{2}} , and g 3 {\displaystyle g_{3}} from S {\displaystyle \mathbb {S} } to S ′ {\displaystyle \mathbb {S} '} such that g 1 ( x ⋅ y ) = g 2 ( x ) ∘ g 3 ( y ) {\displaystyle g_{1}(x\cdot y)=g_{2}(x)\circ g_{3}(y)} for all x , y ∈ S {\displaystyle x,y\in \mathbb {S} } .