T-Color-critical

[math]\displaystyle{ t }[/math]-Color-critical --- [math]\displaystyle{ t }[/math]-цвето-критическиий.

If [math]\displaystyle{ \chi(G)=t }[/math] and [math]\displaystyle{ \chi(H) \lt t }[/math] for every proper subgraph [math]\displaystyle{ H }[/math] of [math]\displaystyle{ G }[/math], then [math]\displaystyle{ G }[/math] is said to be [math]\displaystyle{ t }[/math]-color-critical.

[math]\displaystyle{ G }[/math] is [math]\displaystyle{ t }[/math]-immersion-critical if [math]\displaystyle{ \chi(G) = t }[/math] and [math]\displaystyle{ \chi(H) \lt t }[/math] whenever [math]\displaystyle{ H }[/math] is properly immersed in [math]\displaystyle{ G }[/math].