(* ID:         $Id$ *)

theory Functions imports Main begin

ML "Pretty.margin_default := 64"

text{*

@{thm[display] id_def[no_vars]}

\rulename{id_def}

@{thm[display] o_def[no_vars]}

\rulename{o_def}

@{thm[display] o_assoc[no_vars]}

\rulename{o_assoc}

*}

text{*

@{thm[display] fun_upd_apply[no_vars]}

\rulename{fun_upd_apply}

@{thm[display] fun_upd_upd[no_vars]}

\rulename{fun_upd_upd}

*}

text{*

definitions of injective, surjective, bijective

@{thm[display] inj_on_def[no_vars]}

\rulename{inj_on_def}

@{thm[display] surj_def[no_vars]}

\rulename{surj_def}

@{thm[display] bij_def[no_vars]}

\rulename{bij_def}

*}

text{*

possibly interesting theorems about inv

*}

text{*

@{thm[display] inv_f_f[no_vars]}

\rulename{inv_f_f}

@{thm[display] inj_imp_surj_inv[no_vars]}

\rulename{inj_imp_surj_inv}

@{thm[display] surj_imp_inj_inv[no_vars]}

\rulename{surj_imp_inj_inv}

@{thm[display] surj_f_inv_f[no_vars]}

\rulename{surj_f_inv_f}

@{thm[display] bij_imp_bij_inv[no_vars]}

\rulename{bij_imp_bij_inv}

@{thm[display] inv_inv_eq[no_vars]}

\rulename{inv_inv_eq}

@{thm[display] o_inv_distrib[no_vars]}

\rulename{o_inv_distrib}

*}

text{*

small sample proof

@{thm[display] ext[no_vars]}

\rulename{ext}

@{thm[display] fun_eq_iff[no_vars]}

\rulename{fun_eq_iff}

*}

lemma "inj f \<Longrightarrow> (f o g = f o h) = (g = h)";

  apply (simp add: fun_eq_iff inj_on_def)

  apply (auto)

  done

text{*

\begin{isabelle}

inj\ f\ \isasymLongrightarrow \ (f\ \isasymcirc \ g\ =\ f\ \isasymcirc \ h)\ =\ (g\ =\ h)\isanewline

\ 1.\ \isasymforall x\ y.\ f\ x\ =\ f\ y\ \isasymlongrightarrow \ x\ =\ y\ \isasymLongrightarrow \isanewline

\ \ \ \ (\isasymforall x.\ f\ (g\ x)\ =\ f\ (h\ x))\ =\ (\isasymforall x.\ g\ x\ =\ h\ x)

\end{isabelle}

*}

text{*image, inverse image*}

text{*

@{thm[display] image_def[no_vars]}

\rulename{image_def}

*}

text{*

@{thm[display] image_Un[no_vars]}

\rulename{image_Un}

*}

text{*

@{thm[display] image_compose[no_vars]}

\rulename{image_compose}

@{thm[display] image_Int[no_vars]}

\rulename{image_Int}

@{thm[display] bij_image_Compl_eq[no_vars]}

\rulename{bij_image_Compl_eq}

*}

text{*

illustrates Union as well as image

*}

lemma "f`A \<union> g`A = (\<Union>x\<in>A. {f x, g x})"

by blast

lemma "f ` {(x,y). P x y} = {f(x,y) | x y. P x y}"

by blast

text{*actually a macro!*}

lemma "range f = f`UNIV"

by blast

text{*

inverse image

*}

text{*

@{thm[display] vimage_def[no_vars]}

\rulename{vimage_def}

@{thm[display] vimage_Compl[no_vars]}

\rulename{vimage_Compl}

*}

end