 König's theorem (set theory)

If ${\kappa }_i<{\lambda }_i$ for every $i\in I$, thenThe injection uses functions supported at one coordinate. For non-surjectivity, given any map from the disjoint union to the product, choose at coordinate $i$ a value omitted by the $i$th row; the resulting diagonal element is outside its image.

König's theorem is an important result in set theory and combinatorial set theory, specifically related to the study of infinite trees. The theorem states the following: If \( T \) is an infinite tree of finite height such that every node in \( T \) has a finite number of children, then \( T \) has either: 1. An infinite branch (a path through the tree that visits infinitely many nodes), or 2.