Some Remarks onWriting Mathematical Proofs John M. Write downthedenitionsveryexplicitly write down the things you are allowed to assume and write it all down in careful mathematical language. So begineqnarray 4xyzw 2cdot2tu le 2cdott2u2 2cdotxy2zw2 2cdotx2y2z2w2 2x2y22z2w2 le x22y22z22w22 x4y4z4w4 endeqnarray endproof.
To put the QED.
You can specify lengths as a number times a ariablev where multiplication is denoted by adjacency. Clearly mark the anchors of the induction proof. Lets prove that q C 1 1 q qn 1 qn 1 1 q. Over the years the mathematical community has agreed upon a number of more-or-less standard conventions for proof writing.