Talk:Tensor reshaping

Wrong content
The article defines a "projection"
 * $$\begin{align}\Pi:& V_1\otimes V2\to V_1\\ &\Pi(x\otimes y)=x\end{align}.$$

Such a mapping cannot exist. In fact, as $$(2x)\otimes y= x\otimes (2y),$$ this would imply $$x=2x,$$ even for a nonzero $$x.$$ D.Lazard (talk) 10:12, 19 January 2020 (UTC)

What you state is correct. The correct way to define it is to choose any element from the preimage of $$\otimes: V_1 \times \cdots \times V_n \to V_1 \otimes \cdots \otimes V_n$$, then take the appropriate coordinate projections $$\Pi_{S_i}$$ and then tensor them. A reference to Landsberg, Tensors: Geometry and Applications, 2012 could be added as a source. Ntheazk (talk) 21:53, 28 January 2020 (UTC)