Letter to the Editor by John Derbyshire

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Mathematics Magazine
October 1997 (Vol. 70, No. 4)
Repeated powers:  a comment in verse

Another reader, John Derbyshire (Huntington, NY) commented--in the form of a Petrarchan sonnet--on The limit of x^x^ ... ^x as x tends to zero, J. Marshall Ash, this MAGAZINE 69, June 96, as follows:

When x is raised to power of x we see
The first step of an iteration which
Can then be carried on without a glitch
For ever.  In the range of powers of e
From minus e itself to e inverted
These endless tottering stairs of shrinking x's
Converge!  And yet one question still perplexes:
Beyond that range, what facts can be asserted?
J. Marshall Ash, a scholar from DePaul
Has shown us that, when x is microscopic,
The even steps climb up without a stall
To one; the odd steps, likewise asymptotic,
Decline to zero.  Thanks go out from all
For shedding light upon this curious topic.

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