-clean:
- $(RM) $(foreach DOC,$(DOCS),$(addprefix $(DOC).,aux log fmt toc bbl blg run.xml out pdf snm nav snm vrb glo tdo alg acn acr glg gls xdy))
+img/%.png: fig/%.dot
+ dot -Tpng $< > $@
+
+clean: $(DOCS:%=clean-%)
+ $(RM) $(FIGURES)
+
+clean-%:
+ $(RM) $(addprefix $(@:clean-%=%).,acn acr alg aux bbl blg fmt glg glo\
+ gls ist lof log lol lot mlog out pdf tdo toc)