"which he deduced" is a grammatically correct and usable phrase in written English.
It can be used in a sentence to indicate that something was inferred or concluded by someone. Example: "The detective carefully examined the evidence, from which he deduced that the suspect was not telling the truth."
And he unleashed an uncanny marketing ability in which he deduced his critics' weak points and distilled those to nicknames that stuck.
The manuscript is the account by Gregor Mendel of the pea-breeding experiments from which he deduced the laws of heredity and laid the foundations of modern genetics.
Mr. Mitford said he was surprised at the lack of sartorial elegance, from which he deduced that his customers must be, for the most part, members of the Fourth Estate.
Mr Frydd of the Forensic Science Laboratory was very sceptical about the signatures which he deduced were "not in the least bit likely to have been made by Ronald Biggs".
Dr. Khorana used chemical synthesis to combine the letters into specific defined patterns, like UCUCUCUCU, from which he deduced that UCU encoded for serine and CUC encoded for leucine.
was proved by Tchebychev, from which he deduced that (s - 1)ζ(s) has limit one as s → 1.
Tintinologists cannot get enough of these buried treasures, and I applaud Tom McCarthy for the logical rigor with which he deduces that the jewel embedded in the title of "The Castafiore Emerald" is, in fact, Bianca Castafiore's clitoris.
Think of the scene in Spielberg's "Lincoln"in which he deduces the necessity for equality from the same axiomatic premises he recalls from reading Euclid's "Elements" as a young man.
Bruce Bartlett (Op-Ed, Aug. 22) worries that Al Gore's preference for tying tax cuts to specific taxpayer behavior is little different from direct spending; he then contrasts that proposal to George W. Bush's across-the-board cuts, a difference from which he deduces an ultimately lower cost for the Bush plan.
After discovering an air chamber underneath them, which he had deduced, Hines begun the tunneling effort.
The behavioral economist, Alessandro Acquisti, conducted an experiment in which he could deduce the Social Security numbers of a great many people just by looking at their Facebook profiles — and crawling the Web for the other information that had accrued about them online.
