06_boolean_ops.el

(print (and t t))
(print (and t nil))
(print (or t t))
(print (or t nil))
(print (or nil nil t nil))
(print (or nil nil nil nil))
(print (not nil))
(print (not t))

(setq x 10)
(print (if (> x 0) "kladne"))

(setq y 0)
(print (if (> y 0) "kladne"))

(setq x 10)
(print (and (> x 0) "kladne"))

(setq y 0)
(print (and (> y 0) "kladne"))