Idiomatic Proof by Contradiction in Isabelle? -


so far wrote proofs contradiction in following style in isabelle (using pattern jeremy siek):

lemma "<expression>" proof -   {     assume "¬ <expression>"     have false sorry   }   show ?thesis blast qed

is there way works without nested raw proof block { ... }?

there rule ccontr classical proofs contradiction:

have "<expression>" proof (rule ccontr)   assume "¬ <expression>"   show false sorry qed

it may use by contradiction prove last step.

there rule classical (which looks less intuitive):

have "<expression>" proof (rule classical)   assume "¬ <expression>"   show "<expression>" sorry qed

for further examples using classical, see $isabelle_home/src/hol/isar_examples/drinker.thy


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