A copy of this work was available on the public web and has been preserved in the Wayback Machine. The capture dates from 2018; you can also visit the original URL.
The file type is
If the commutative ring 5 is the fibre product of Rx and R2 over R, and if R2 maps onto R, then the fundamental group of S is the profinite free product of the fundamental groups of R¡ and R2 with the fundamental group of R amalgamated. Van Kampen's theorem in algebraic topology asserts that, under suitable hypotheses, if Y->X1doi:10.2307/2039579 fatcat:7x77qnlt5ngtpb3yi46h3hcaxq