Esther Rantzen Esther Rantzen Dame Esther Louise Rantzen (born 22 June 1940) is an English journalist and television presenter, who presented the BBC television series "That's Life!" for 21 years, from 1973 until 1994. She works with various charitable causes, and founded the charities ChildLine, promoting child protection, which she set up in 1986, and The Silver Line, designed to combat loneliness, which she set up in 2012. Rantzen was born in Berkhamsted, Hertfordshire, England, to Katherine Flora Rantzen ("née" Leverson, 1911–2005) and Henry Barnato Rantzen (1902–1992). She has one younger sister, Priscilla N. Taylor. She attended Buckley Country Day School in
Well-founded relation context of the natural numbers, this means that the relation <, which is well-founded, is used instead of the relation ≤, which is not. In some texts, the definition of a well-founded relation is changed from the definition above to include this convention. Well-founded relation In mathematics, a binary relation, "R", is called well-founded (or wellfounded) on a class "X" if every non-empty subset "S" ⊆ "X" has a minimal element with respect to "R", that is an element "m" not related by "sRm" (for instance, ""s" is not smaller than "m"") for any "s" ∈ "S". In other words,