let G be V9() Matrix of (TOP-REAL 2); :: thesis: ( G is X_equal-in-line implies v_strip G,(len G) = { |[r,s]| where r, s is Real : (G * (len G),1) `1 <= r } )
assume A1: G is X_equal-in-line ; :: thesis: v_strip G,(len G) = { |[r,s]| where r, s is Real : (G * (len G),1) `1 <= r }
0 <> width G by GOBOARD1:def 5;
then 1 <= width G by NAT_1:14;
hence v_strip G,(len G) = { |[r,s]| where r, s is Real : (G * (len G),1) `1 <= r } by A1, GOBOARD5:10; :: thesis: verum