let f be non constant standard special_circular_sequence; :: thesis: for i, j being Element of NAT st i <= len (GoB f) & j <= width (GoB f) holds
Int (cell (GoB f),i,j) c= (L~ f) `
let i, j be Element of NAT ; :: thesis: ( i <= len (GoB f) & j <= width (GoB f) implies Int (cell (GoB f),i,j) c= (L~ f) ` )
assume ( i <= len (GoB f) & j <= width (GoB f) ) ; :: thesis: Int (cell (GoB f),i,j) c= (L~ f) `
then Int (cell (GoB f),i,j) misses L~ f by GOBOARD7:14;
hence Int (cell (GoB f),i,j) c= (L~ f) ` by SUBSET_1:43; :: thesis: verum