If {x,{x,y}}={z,{z,t}} then x=z and y=t must be?
10444
If $\{x,\{x,y\}\} = \{z, \{z,t\}\}$, then must it be $x = z$ and $y = t$?
3072
If the empty set is a subset of every set, why isn't $\{\emptyset,\{a\}\}=\{\{a\}\}$?
45370
Is it true that $|d(x, z) - d(y, z)| \leq d(x, y)$ and how do I prove it?
110443
Simplifying P(x|y,z) to P(x|z)
128989
Is ${\bf Z} \times {\bf Z}$ elementarily equivalent to ${\bf Z}$?
100844
How should I understand "$A$ unless $B$"?
153355
Given $S \in B(Y^{*}, X^{*})$, does there exist $T\in B(X,Y)$ such that $S=T^{*}$?
8094
X, Y, Z — horizontal, vertical and ...?
111763
True or False $A - C = B - C $ if and only if $A \cup C = B \cup C$
140977
Why $\bar{z_1}z_2+\bar{z_2}z_3+\bar{z_3}z_1 \in \mathbb R \iff z_1, z_2, z_3 \text{ are along the same line}$
102175
$Z=XY$, $E_Z[Z]$, $E_{X,Y}[XY]$
58242
Does $[x]\cdot [y]=[xy]$? Here $[.]$ is the GIF
16948
Need help with a proof that if $xy=0$ then $x=0$ or $y=0$
77902
If $A,B,$ and $C$ are sets, then $A\times(B-C)$ = $(A \times B)$ $-$ $(A \times C)$.
154698
Union of Cartesian products: $X \times (Y \cup Z)= (X \times Y) \cup(X\times Z)$
76823
Is it the case that for all sets $A, B, C,$ and $D$, $(A \times B) \cup (C \times D) = (A \cup B) \times (C \cup D)$?
66563
Is $ (A∪B)×(C∩D)=(A∪C)×(B∪D)$ true for all sets A,B,C and D?